Pulley rotatingly supporting device

ABSTRACT

The object of the invention is to provide a structure which not only can be reduced in size but also can secure the durability of an endless belt ( 11 ) to be provided on a driven pulley ( 4   b ) and a pulley rotation support apparatus for supporting the driven pulley ( 4   b ).  
     In the invention, as the above pulley rotation support apparatus, there is used a three-point-contact-type or four-point-contact-type radial ball bearing ( 14   b ). An offset quantity δ, which is an axial-direction distance between the center α of a radial load applied from the endless belt ( 11 ) to the driven pulley ( 4   b ) and the center position β of the radial ball bearing ( 14   b ), is set 40% or less of the pitch circle diameter of the radial ball bearing ( 14   b ). The radial clearance of this radial ball bearing ( 14   b ) is set 0.2% or less of the above pitch circle diameter.

TECHNICAL FIELD

A pulley rotation support apparatus according to the invention is usedto support a pulley, on which there is disposed a belt to be driven androtated by an engine for e.g. a car, on a fixed part of the car in sucha manner that the pulley can be rotated with respect to the fixed part.

BACKGROUND ART

Conventionally, an automatic tensioner has been used in order to adjustthe tensile force of a timing belt or an auxiliary machine driving beltused in a car engine, and the thus-adjustable belt has been used todrive an auxiliary machine such as a compressor. And, in a rotationsupport part for a pulley for use in the automatic tensioner or a drivenpulley for driving the above auxiliary machine, there is supported suchpulley on a fixed part using a rolling bearing in such a manner that thepulley can be rotated with respect to the fixed part.

For example, FIG. 32 shows a first example of conventional structures inwhich a double-row rolling element bearing is used in the rotationsupport part of a compressor to be incorporated into a car airconditioner to thereby compress a refrigerant. A rotary shaft 1 of thiscompressor is rotatably supported within a case 2 by a rolling bearing(not shown). On the periphery of a support tube part 3 formed in theouter surface of the end portion of the casing 2 and corresponding to asupport part as set forth in the appended claims, there is rotatablysupported a driven pulley 4 using a double-row radial ball bearing 5.The driven pulley 4 is structured such that it has a U-shaped sectionand it is formed in a circular-ring shape as a whole; and, a solenoid 6fixed to the end face of the casing 2 is disposed in the internal spaceof the driven pulley 4. On the other hand, to the portion of the endportion of the above rotary shaft 1 that is projected from the abovecasing 2, there is fixed a mounting bracket 7; and, on the periphery ofthis mounting bracket 7, there is supported a ring-shaped plate 8 madeof magnetic material through a plate spring 9. The ring-shaped plate 8,when the solenoid 6 is not energized electrically, is separated a partfrom the above driven pulley 4 due to the elastic force of the platespring 9, as shown in FIG. 32; and, on the other hand, when the solenoid6 is energized, the ring-shaped plate 8 is attracted toward this drivenpulley 4 to be thereby be able to transmit the rotation power from thisdriven pulley 4 to the above rotary shaft 1. That is, the solenoid 6,ring-shaped plate 8 and plate spring 9 cooperate together inconstituting an electromagnetic clutch 10 which is used to engage theabove driven pulley 4 and the above rotary shaft 1 with each other anddisengage them from each other.

According to the above-mentioned structure in which the driven pulley 4is rotatably supported using the double-row radial ball bearing 5, evenin case where a small level of partial load is applied to this drivenpulley 4 from an endless belt 11 provided on this driven pulley 4, thereis little possibility that the center axes of an outer ring 12 and aninner ring 13 respectively constituting the above double-row radial ballbearing 5 can be incongruous with each other (can be inclined withrespect to each other). Therefore, not only the durability of the abovedouble-row radial ball bearing 5 can be secured sufficiently but alsothe rotation center of the above driven pulley 4 can be preventedagainst inclination, thereby being able to prevent the above endlessbelt 11 against partial wear.

However, use of the above double-row radial ball bearing 5 inevitablyincreases the axial-direction dimension of the above structure. Therotation support part of the above driven pulley 4, in many cases, mustbe disposed in a limited space and thus the increase in theaxial-direction dimension is not desirable. Also, the increase in theaxial-dimension increases the costs of the composing parts of thestructure.

In case where, as a rolling bearing for supporting the above drivenpulley 4, instead of the above double-row radial ball bearing 5, thereis used a single-row deep-groove-type radial ball bearing, theaxial-direction dimension of the structure can be reduced to thereby beable to facilitate the installation of the rotation support part of thebearing in a limited space. However, in the case of a simple single-rowdeep-groove-type radial ball bearing, when a moment load is applied tothe above driven pulley 4, there is obtained a small force to preventthe inclination of this driven pulley 4, which greatly increases thedegree of incongruity between the center axes of the outer and innerrings respectively constituting the above radial ball bearing. As aresult of this, not only the durability of the above radial ball bearingis insufficient but also great partial wear is easy to occur in theendless belt 11 arranged on the above driven pulley 4.

In view of the above circumstances, conventionally, there are proposedstructures, as disclosed in the following patent reference 1 and patentreference 2, in which a single-row four-point-contact-type radial ballbearing is used to support a driven pulley. Here, FIGS. 33 and 34 showsa second example of the conventional structures disclosed in the patentreference 1.

According to the second example of the conventional structures, a drivenpulley 4 a, which is formed by enforcing a bending working operationsuch as a press working operation on a metal plate, can be rotatablysupported on the periphery of a support part (not shown) using asingle-row four-point-contact-type radial ball bearing 14. This radialball bearing 14 comprises an outer ring 15 and an inner ring 16supported so as to be concentric with each other, and two or morerolling elements 17, 17. Of these composing elements, in the innerperipheral surface of the outer ring 15, there is formed an outerraceway 16 and, in the outer peripheral surface of the inner ring 15,there is formed an inner raceway 19 in such a manner that theyrespectively extend over the entire peripheries of their associatedperipheral surfaces. The section shapes of the respective raceways 18and 19 are respectively so called Gothic arch shapes in which two arcseach having a radius of curvature larger than one half of the diametersof the respective rolling elements 17, 17. Therefore, the respectiveraceways 18, 19 and the rolling surfaces of the respective rollingelements 17, 17 are contacted with each other respectively at twopoints, that is, at a total of four points in every rolling elements 17,17.

The thus-structured four-point-contact-type radial ball bearing 14 islarge in rigidity with respect to the moment load when compared with anordinary single-row deep-groove-type radial ball bearing and, even whenthe moment load is applied thereto, the center axes of the outer ring 15and inner ring 16 are difficult to shift from each other. Thanks tothis, when compared with a structure in which a pulley rotation supportdevice for a compressor is formed using an ordinary single-rowdeep-groove-type radial ball bearing, there can be eased the partialwear that occurs in the endless belt 11 (see FIG. 32) arranged on thedriven pulley 4. By the way, in the patent reference 2, there isdisclosed a structure in which the above-structuredfour-point-contact-type radial ball bearing is assembled to the rotationsupport part of a driven pulley for driving a compressor and further,between the driven pulley and the rotary shaft of the compressor, thereis interposed an electromagnetic clutch.

Also, in the case of such a single-row three-point-contact-type rollingelement bearing 14 a as shown in FIG. 35 as well, it has larger rigiditywith respect to the moment load than an ordinary single-rowdeep-groove-type radial ball bearing and thus, even when it receives themoment load, the center axes of an outer ring 15 and inner ring 16 a aredifficult to shift from each other. According to the single-rowthree-point-contact-type rolling element bearing 14 a, in the outerperipheral surface of the inner ring 16 a, there is formed an arc-shapedinner raceway 19 a, whose section to be contacted with the rollingsurface of the rolling element 17 at a point has a single curvature;and, in the inner peripheral surface of the outer ring 15, similarly tothe four-point-contact-type radial ball bearing 14 shown in theabove-illustrated FIGS. 33 and 34, there is formed a Gothic-arch-shapedouter raceway 18 which is to be contacted with the rolling surface ofthe rolling element 17 at two points. In the structure in which a pulleyfor a compressor is supported using the thus-formedthree-point-contact-type rolling element bearing 14 a, when comparedwith the structure in which a pulley rotation support device for acompressor is formed using an ordinary single-row deep-groove-typeradial ball bearing, there can be eased the partial wear that occurs inthe endless belt 11 (see FIG. 32) provided on the driven pulley 4. Asimilar effect can also be obtained in a three-point-contact-typerolling element bearing having a structure in which, contrary to thestructure shown in FIG. 5, the rolling surfaces of the respectiverolling elements are contacted with an outer raceway at a point and arecontacted with an inner raceway at two points.

As described above, when the above-mentioned three-point-contact-type orfour-point-contact-type radial ball bearing is assembled to the rotationsupport part of the pulley, there is a possibility that the reduction inthe size and weight of the structure and the durability thereof arecompatible with each other on a high level. However, in the case of theconventional structures, since the factors and elements of therespective parts thereof are not examined to the full, there cannot bealways obtained a sufficient effect.

Also, in the case of an auxiliary machine for an engine, especially, inthe case of a compressor, recently, there have been made improvementssuch as an increase in the rotation thereof, an increase in the capacitythereof, and a decrease in the axial-direction dimension thereof.However, when the auxiliary machine is improved in the rotation thereofand the like, a rolling element bearing for supporting a pulley for theauxiliary machine is easy to generate heat, which reduces the seizurelife (deterioration life) of grease. Also, since an excessively largemoment load is applied to the rolling element bearing, the rollingelements are easy to run up onto the shoulder portions of an outerraceway and an inner raceway. Further, in the case of other machinesthan the auxiliary machines of the engine, for example, in the case ofan automatic tensioner as well, when an increase in the rotation thereofor a reduction in the axial-direction dimension is required, in arolling element bearing for supporting a pulley which is used in suchmachine, similarly, the seizure life of grease can be shortened or therolling elements are easy to run up onto the shoulder portions of theouter raceway and inner raceway. Therefore, in a rolling element bearingto be used in the machine such as an engine auxiliary machine which isrequired for an increase in the rotation and capacity thereof as well asis required for a reduction in the size thereof, when no considerationis given at all to an increase in the seizure life of the grease and arun-up allowance of the rolling element (a ratio which expresses thedifficulty for the rolling element to run up onto the shoulders of theraceways), there is a possibility that these performances of the rollingelement bearing can be insufficient. By the way, in case where theseizure life of the grease is sufficiently long, since the life of thebearing is determined by the rolling fatigue lives of the inner ring andouter raceways, to enhance the seizure life of the grease is notspecially important. However, in case where the seizure life is not longso much, because there is a possibility that the bearing life can bedetermined by this seizure life, from the viewpoint of securing thebearing life, to enhance the seizure life is especially important.

In view of the above circumstances of the conventional pulley rotationsupport apparatus, according to the invention, there is provided apulley rotation support apparatus which not only can secure thedurability of a rolling bearing and an endless belt arranged on a pulleybut also, even when it is used in a machine required for an increase inthe rotation and capacity thereof as well as for a reduction in the sizethereof, can fully secure the seizure life of grease to be charged intothe interior of the rolling bearing as well as the run-up allowance of arolling element.

[Patent Reference 1]

-   JP-A-9-119510    [Patent Reference 2]-   JP-A-11-336795    [Patent Reference 3]-   JP-A-11-210619    [Patent Reference 4]-   JP-UM-A-64-27482

DISCLOSURE OF THE INVENTION

A pulley rotation support apparatus according to the invention,similarly to the previously described conventionally known pulleyrotation support apparatus, comprises a fixed support portion, a rollingbearing supported on the fixed support portion, and a pulley which isrotatably supported by the rolling bearing and also on which an endlessbelt is to be disposed.

And, the above rolling bearing, similarly to the above-mentioned patentreference 1 and patent reference 2, is a single-rowthree-point-contact-type or four-point-contact-type radial ball bearingwhich includes an inner ring having in the outer peripheral surfacethereof an inner raceway formed so as to be contactable with the rollingsurface of a rolling element at one or two points, an outer ring havingin the inner peripheral surface thereof an outer raceway formed so as tobe contactable with the rolling surface of a rolling element at one ortwo points, two or more rolling elements rotatably interposed betweenthe inner raceway and outer raceway, a retainer having pockets forholding the rolling elements in a freely rotatably manner, and a sealplate having an outer peripheral edge portion secured to the innerperipheral surface of the outer ring and also having the leading endportion of a seal lip disposed in the inner peripheral edge portionthereof slidably contacted with the outer peripheral surface of theinner ring, wherein the rolling bearing can be lubricated by alubricant, and also wherein at least one of the inner raceway and outerraceway is to be contacted with the rolling surfaces of the rollingelements respectively at two points. That is, the present inventionprovides a pulley rotation support apparatus using the presentsingle-row three-point-contact-type or four-point-contact-type radialball bearing.

Especially, according to a pulley rotation support apparatus as setforth in claim 1, an off-set quantity, which is an axial-directiondistance between the width-direction central portion position of theportion to be contacted with the above endless belt on the outerperipheral surface of the pulley and the center of the above radial ballbearing, is 40% or less of the pitch circle diameter of the radial ballbearing, the radial clearance of this radial ball bearing when it existsalone is 0.2% or less of the pitch circle diameter of the radial ballbearing, and the pocket opening of the retainer is disposed so as toface in a direction where an offset load is applied to the center ofthis bearing.

Also, in a pulley rotation support apparatus as set forth in Claim 2, anoffset quantity consisting of an axial-direction distance between thewidth-direction central portion position of the outer peripheral surfaceof the pulley that is contacted with the endless belt and the center ofthe radial ball bearing is 40% or less of the pitch circle diameter ofthe radial ball bearing, the radial clearance of the radial ball bearingwhen it is alone is 0.2% or less of the pitch circle diameter of theradial ball bearing, and the above seal plate is structured such that,of the inner surfaces thereof, at least the near-to-outside-diameterportion thereof close to the inner peripheral surface of the outer ringis formed as an inclined surface which is inclined inwardly in the axialdirection as it goes outwardly in the diameter direction, or a concavelycurved surface which is curved in this direction.

Also, in a pulley rotation support apparatus as set forth in Claim 3, anoffset quantity consisting of an axial-direction distance between thewidth-direction central portion position of the outer peripheral surfaceof the pulley that is contacted with the endless belt and the center ofthe radial ball bearing is 40% or less of the pitch circle diameter ofthe radial ball bearing, the radial clearance of the radial ball bearingwhen it is alone is 0.2% or less of the pitch circle diameter of theradial ball bearing, and at least one of the seal lips of the seal plateincludes a substantially-circular-ring-shaped main body portion and aprojecting portion formed in the inner peripheral edge portion of themain body portion so as to project outwardly in the axial directionsubstantially over the entire periphery thereof, the main body portionof the present seal lip except for the projecting portion thereof, inits free state, is inclined outwardly in the axial direction as it goestoward the inner peripheral edge portion thereof, and, in the assembledstate thereof, the leading end edge of the projecting portion isslidably contacted with the axial-direction outer side wall surface of aseal groove formed over the entire periphery of part of the outerperipheral surface of the inner ring substantially over the entireperiphery of the present side wall surface.

And, in a pulley rotation support apparatus as set forth in Claim 4, anoffset quantity consisting of an axial-direction distance between thewidth-direction central portion position of the outer peripheral surfaceof the pulley that is contacted with the endless belt and the center ofthe radial ball bearing is 40% or less of the pitch circle diameter ofthe radial ball bearing, the radial clearance of the radial ball bearingwhen it is alone is 0.2% or less of the pitch circle diameter of theradial ball bearing, and at least one of the two seal plates isstructured such that, in the portion of the leading end face of the seallip that is opposed to the axial-direction outer side wall surface of aseal groove, there is formed a rectangular-shaped or arc-shaped cut-awayportion allowing the air to pass into the inside thereof, the leadingend portion of this seal lip is surface contacted with theaxial-direction outer side wall surface of a seal groove substantiallyover the entire periphery thereof, and, regarding to the cut-awayportion, in case where the depth thereof from the leading end edge ofthe seal lip is expressed as L₁, the length in the circumferentialdirection thereof is expressed as L₂, and the diameter of the rollingelement is expressed as D_(a), the relationship “L₁≦0.09D_(a), andL₂≦0.18D_(a)” can be satisfied.

According to the above-structured pulley rotation support apparatus ofthe invention, it is possible to prevent the center axes of the innerring and outer ring respectively constituting the radial ball bearingfrom shifting from each other. That is, since the offset quantity of thewinding position of the endless belt with respect to the center of theabove radial ball bearing is restricted to 40% or less of the pitchcircle diameter of this radial ball bearing, the moment load to beapplied to the above outer ring through the pulley can be controlleddown to a small value. Due to this, the inclination of the pulley andouter ring with respect to the above inner ring can be controlled tothereby prevent an excessive surface pressure from acting on the rollingcontact portion of the above radial ball bearing, which makes itpossible to secure the durability of this radial ball bearing. Also, thepartial wear of the endless belt provided on the above pulley can becontrolled to thereby be able to secure the durability of this endlessbelt as well. Also, because the radial clearance of the above radialball bearing when it exists alone is restricted to 0.2% or less of thepitch circle diameter of this radial ball bearing, the above two centeraxes are hard to shift from each other, so that the above operation canbe obtained in a better condition. Therefore, even when the presentradial ball bearing is used in an apparatus required for an increase inthe rotation thereof, an increase in the capacitance thereof and areduction in the size thereof, such as a compressor for a car airconditioner, the seizure life of grease to be charged into the interiorof the rolling bearing and the run-up allowance of the ball can besecured sufficiently.

Also, since the pocket opening of the above retainer is disposed to facein the direction where the offset load is applied to the center of thebearing and thus an offset radial load is applied to the center of thebearing, the grease existing around the load area, during the operationof the bearing, is circulated actively from the inner raceway on thepocket opening side of the retainer to the outer raceway; and,therefore, when the bearing receives the offset load, the seizure lifeof the grease can be extended and thus the performance of the bearingcan be enhanced.

Also, since, of the inner surfaces of the above seal plate, at least thenear-to-outside-diameter portion thereof close to the inner peripheralsurface of the outer ring is formed as an inclined surface which isinclined inwardly in the axial direction as it goes outwardly in thediameter direction, or a concavely curved surface which is curved inthis direction, there is eliminated the possibility that a largequantity of grease can stay on the inner surface of the seal plate, sothat the grease, which exists between the above outer raceway and innerraceway and is charged into the space with the above respective rollingelements stored therein, can be circulated smoothly within this space.That is, because, of the inner surfaces of the above seal plate, thenear-to-outside-diameter portion thereof close to the inner peripheralsurface of the outer ring is formed as an inclined surface which isinclined inwardly in the axial direction as it goes outwardly in thediameter direction, or a concavely curved surface which is curved inthis direction, the grease, which has adhered to the inner surface ofthe above seal plate and has moved to the outside-diameter side of theseal plate due to a centrifugal force, is guided to the above outerraceway formed in the inner peripheral surface of the above outer ring.This can prevent a large quantity of grease from staying on the innersurface of the seal plate, so that the grease charged into the abovespace can be circulated within the above space including the rollingcontact portions between the above outer ring and inner raceways and therolling surfaces of the respective rolling elements. Due to this, all ofthe grease charged into the above space is used for lubrication of theabove rolling contact portions, thereby being able to retard thedegradation of the grease (being able to enhance the durability of thegrease) for lubrication of these rolling contact portions when comparedwith the conventional structure.

Also, according to the invention, at least one of the seal lips of theseal plate includes a substantially-circular-ring-shaped main bodyportion and a projecting portion formed in the inner peripheral edgeportion of the main body portion so as to project outwardly in the axialdirection substantially over the entire periphery thereof (except forthe slight cut-away portion), the main body portion of the present seallip except for the projecting portion thereof, in its free state, isinclined outwardly in the axial direction as it goes toward the innerperipheral edge portion thereof, and, in the assembled state thereof,the leading end edge of the projecting portion is slidably contactedwith the axial-direction outer side wall surface of a seal groove formedover the entire periphery of part of the outer peripheral surface of theinner ring substantially over the entire periphery of the present sidewall surface. Thanks to this, even in case where the pressure (internalpressure) of the space with the respective rolling elements storedtherein is increased due to an increase in the temperature or the likewhen the bearing is in operation, there is eliminated the possibilitythat the contact pressure between the leading end edge of the projectingportion formed in the seal lip and the outer side wall surface of theseal groove formed in the outer peripheral surface of the inner ring canlower, or there can be generated a clearance between them. Rather, whenthe above internal pressure rises, since the leading end edge of theabove projecting portion is pressed against the outer side wall surfaceof the above seal groove, the sealing performance of the bearing canenhanced further. Also, because the leading end edge of the projectingportion formed in the peripheral edge portion of the above seal lip soas to project in the axial direction is slidably contacted with theabove outer side wall surface, the present leading end edge and outerside wall surface can be easily contacted with each other in a stablemanner. Further, in a state where the above seal lip is held in its freecondition, the main body portion of the seal lip except for theprojecting portion thereof is inclined outwardly in the axial directionas it goes for the inner peripheral edge portion thereof. This canincrease the force for pressing the above projecting portion against theabove outer side wall surface. Also, in a state where the leading endedge of this projecting portion is slidably contacted with this outerside wall surface, the main body portion except for the above projectingportion can be easily inclined outwardly in the axial direction as itgoes for the inner peripheral edge portion, or can be made to coincidewith a virtual plane which intersects the center axis of the presentseal plate at right angles. Thanks to this, even in case where thebearing is used while the outer ring is rotating at high speed and thusa centrifugal force is applied to the inner peripheral edge portion ofthe seal lip including the above projecting portion, this innerperipheral edge portion can be prevented from shifting in a directionwhere it parts away from the outer side wall surface of the above sealgroove. As a result of this, even under severe conditions where a largepartial load is applied, the temperature rises, the outer ring rotatesat a high speed, and the like, the sealing performance of the rollingbearing with a seal plate can be secured sufficiently. Therefore, whenthe rolling bearing is used with grease charged into the interiorthereof, not only base oil contained in this grease can be preventedfrom leaking out to the outside but also this base oil can be preventedfrom being oxidized by the air in the outside, thereby being able toenhance the life of this grease. Further, various foreign substancesexisting in the outside can be prevented from entering the space withthe respective rolling elements stored therein, thereby being able toprevent the respective raceways and the rolling surfaces of therespective rolling elements against damage.

Also, according to the invention, at least one of the two seal plates isstructured such that, in the portion of the leading end face of the seallip that is opposed to the axial-direction outer side wall surface of aseal groove, there is formed a rectangular-shaped or arc-shaped cut-awayportion allowing the air to pass into the inside thereof, the leadingend portion of this seal lip is surface contacted with theaxial-direction outer side wall surface of a seal groove substantiallyover the entire periphery thereof, and, regarding to the cut-awayportion, in case where the depth thereof from the leading end edge ofthe seal lip is expressed as L₁, the length in the circumferentialdirection thereof is expressed as L₂, and the diameter of the rollingelement is expressed as D_(a), the relationship “L₁≦0.09D_(a), andL₂≦0.18D_(a)” can be satisfied. Thanks to this structure, the contactarea between the leading end edge of the seal lip and the side wallsurface of a seal groove formed in the outer peripheral surface of aportion of the inner ring can be increased. Therefore, sufficientsealing performance can be secured under the severe conditions and, whenthe ball bearing is used while grease is charged into the interiorthereof, not only the base oil contained in this grease can be preventedfrom leaking out to the outside but also this base oil can be preventedagainst oxidization, thereby being able to enhance the life of thisgrease. Further, various foreign substances existing in the outside canbe prevented from entering the space with the respective rollingelements stored therein, thereby being able to prevent the respectiveraceways and the rolling surfaces of the respective rolling elementsagainst damage. Further, when in use, even in case where the internalpressure of the ball bearing with a seal plate tends to rise, the air ofthe interior of the ball bearing can be discharged to the outside,thereby being able to prevent the internal pressure from rising. Thiscan prevent the seal lip from turning up, so that the sealingperformance by this seal lip can be stabilized. Also, because thedimension of the above cut-away portion is restricted down to a smallvalue, invasion of the air from the outside through this cut-awayportion can be restricted (down to a small level). Therefore, regardlessof the existence of this cut-away portion, the grease charged into theinterior of the ball bearing can be prevented against oxidization.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial section view of a first embodiment of the mode forcarrying out the invention;

FIG. 2 is a partially enlarged section view of only the radial ballbearing taken out from the first embodiment;

FIG. 3 is a diagrammatic view of the results of an endurance testconducted in order to know the influence of a ratio between an off-setquantity and pitch circle diameter on the durability of the radial ballbearing;

FIG. 4 is a partially enlarged section view of a first example of athree-point-contact-type radial ball bearing;

FIG. 5 is a partially enlarged section view of a second example of theradial ball bearing;

FIG. 6 is a section view of another example of a structure to which theinvention is applied;

FIG. 7 is a section view of a half section of a second embodiment of themode for carrying out the invention;

FIG. 8 is a front view of FIG. 7;

FIG. 9 is a half section view of the second embodiment applied to acomparative example;

FIG. 10 is an explanatory view of the results of a durability test;

FIG. 11 is a section view of the second embodiment when it is applied toa pulley of an electromagnetic clutch for a car air conditionercompressor;

FIG. 12 is a section view of a half section of a third embodiment of themode for carrying out the invention;

FIG. 13 is an enlarged view of the A portion shown in FIG. 12;

FIG. 14 is a section view of a half section of a fourth embodiment ofthe mode for carrying out the invention;

FIG. 15 is a section view of a half section of a fifth embodiment of themode for carrying out the invention;

FIG. 16 is a section view of a half section of a sixth embodiment of themode for carrying out the invention;

FIG. 17 is a section view of a half section of a seventh embodiment ofthe mode for carrying out the invention;

FIG. 18 is a section view of a half section of an eighth embodiment ofthe mode for carrying out the invention;

FIG. 19 is a section view of a ninth embodiment of the mode for carryingout the invention;

FIG. 20 is a partially enlarged section view of only the rolling bearingwith a seal plate taken out from the pulley rotation support apparatusof the invention;

FIG. 21 is an enlarged section view of the B portion shown in FIG. 20;

FIG. 22, similarly to FIG. 20, is a section view of a tenth embodimentof the mode for carrying out the invention;

FIG. 23, similarly to FIG. 20, is a section view of an eleventhembodiment of the mode for carrying out the invention;

FIG. 24 is an enlarged section view of the C portion shown in FIG. 23;

FIG. 25 is an enlarged section view of a seal lip in its free state,corresponding to the D portion shown in FIG. 24;

FIG. 26 is a view of the seal lip, when it is viewed from the right sideof FIG. 25;

FIG. 27, similarly to FIG. 29, is a section view of a twelfth embodimentof the mode for carrying out the invention;

FIG. 28 is a section view of the ninth embodiment of the invention,showing a state in which the rolling bearing with a seal plate isincorporated into the rotation support portion of a pulley for acompressor with an electromagnetic clutch incorporated therein;

FIG. 29 is a section view of a thirteenth embodiment of the mode forcarrying out the invention;

FIG. 30 is a section view of a fourteenth embodiment of the mode forcarrying out the invention;

FIG. 31 is an enlarged section view of a half section of only therolling bearing with a seal plate take out from the pulley rotationsupport apparatus shown in FIG. 30;

FIG. 32 is a partial section view of a first example of conventionalstructures;

FIG. 33 is a section view of a second embodiment of the conventionalstructures;

FIG. 34 is a partially enlarged section view of only thefour-point-contact-type radial ball bearing taken out the conventionalpulley rotation support apparatus; and,

FIG. 35 is a partially enlarged section view of only thethree-point-contact-type radial ball bearing taken out from theconventional pulley rotation support apparatus.

By the way, referring to the reference characters in the drawings, 1designates a rotary shaft, 2 a casing, 3 a support tube part, 4, 4 a, 4c a driven pulley, 5 a double-row radial ball bearing, 6 a solenoid, 7 amounting bracket, 8 a ring-shaped plate, 9 a plate spring, 10 anelectromagnetic clutch, 11 an endless belt, 12 an outer ring, 13 aninner ring, 14, 14 a˜14 d a radial ball bearing, 15, 15 a, 15 b an outerring, 16, 16 a˜16 c an inner ring, 17 a rolling element, 18, 18 a, 18 ban outer raceway, 19, 19 a˜19 c an inner raceway, 20 a securing groove,21 a seal ring, 22 a core metal, 23 an elastic member, 24 a seal lip, 25an internal space, 26 a retainer, 27 a rim portion, 28 a pocket, 29 arolling bearing, 30 a damping member, 40 a single-row ball bearing, 41an inner ring, 41 a a first groove, 41 b a second groove, 42 an outerring, 42 a a first groove, 42 b a second groove, 43 a ball (rollingelement), 44 a pocket, 45 a crown-type retainer (retainer), 46 a sealmember, 46 a a core metal, 46 b rubber, 47 a retainer main body, 48 amark, 60 an electromagnetic clutch, 61 a pulley, 62 a compressorhousing, 63 a drive shaft, 64 a rotary disk, 65 a flexible member, 66 anarmature, 67 a cylindrical shaft, 68 a rotor, 69 a driven pulley, 70 anendless belt, 71 a friction surface, 72 a recessed portion, 73 anelectromagnetic coil, 81 a a rolling bearing with a seal plate, 82 aninner raceway, 83 an inner ring, 84 an outer raceway, 85, 85 a an outerring, 86 a rolling element, 87 a retainer, 87 a a retainer, 88 a rimportion, 90 a securing groove, 91 a a seal plate, 91 b a seal plate, 92a space, 93, 93 a a core metal, 94, 94 b, 94 c an elastic member, 98 anoutside-diameter-side inclined surface, 99 a shoulder portion, 100 achamfered portion, 101 an inside-diameter-side inclined surface, 102 ashoulder portion, 103, 103 a an outside-diameter-side concavely curvedsurface, 104 a curved surface portion, a guide portion, 105 an inclinedsurface, 106 an inside-diameter-side concavely curved surface, 108 aflat surface, 109 an outer surface, 110 a clearance, 111 an outersurface, 121 a rotary shaft, 122 a casing, 123 a support tube part, 124a a driven pulley, 125 a, 125 b, 125 c a rolling bearing with a sealplate, 130 an electromagnetic clutch, 132 an outer ring, 133 an innerring, 134 a rolling element, 135 an outer raceway, 136 an inner raceway,137 a securing groove, 138 a a seal plate, 139 a core metal, 140, 163 anelastic member, 143 a seal groove, 144 a, 144 b a side wall surface,148, 148 a a bracket, 149 a ring-shaped member, 150 a small-diameterportion, 151 a large-diameter portion, 152 a stepped portion, 153, 156a˜156 c, 157, 160 a˜160 c a seal lip, 154 a main body portion, 155, 155a a projecting portion, 158 a flat surface portion, 159 a cut-awayportion, 161, 164 a tube-shaped member, 163, 165 a ring-shaped plate,166 a ring-shaped member, 168 a pulley, 170 an inside-diameter-sidecylindrical portion, and 171 a retaining ring, respectively.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, FIGS. 1 and 2 show a first embodiment of the mode for carrying outthe invention, which corresponds to claim 1. By the way, the presentembodiment is characterized in that, in a structure using afour-point-contact-type radial ball bearing 14 b as a rolling bearing ina rotation support part for a driven pulley 4 b, not only the factors ofthe radial ball bearing 14 b are restricted properly but also theposition relationship between this radial ball bearing 14 b and theabove driven pulley 4 b is restricted properly in connection with thefactors of the radial ball bearing 14 b, thereby being able to securethe durability of this radial ball bearing 14 b and an endless belt 11arranged on and over the above driven pulley 4 b. The structures andoperations of the other parts of the present embodiment are similar tothose of the conventional structure shown in the previously describedFIG. 32. Therefore, the same designations are given to the same partsand thus the duplicate description thereof is omitted or simplifiedhere. Accordingly, description will be given below mainly of thecharacteristic portions of the present embodiment.

The radial ball bearing 14 b includes an outer ring 15 a and an innerring 16 b supported so as to be concentric with each other, and two ormore rolling elements 17. Of these composing elements, in the innerperipheral surface of the outer ring 15 a, there is formed an outerraceway 18 a so as to extend over the entire periphery thereof; and, inthe outer peripheral surface of the inner ring 16 b, there is formed aninner raceway 19 b so as to extend over the entire periphery thereof.The shapes of the sections of the two raceways 18 a, 19 b are so calledGothic-arch-like shapes which can be obtained when a pair of arcsrespectively having the radii of curvature Ro, Ri larger than one halfof the diameter Da of each of the rolling elements 17 and also havingdifferent centers are crossed with each other in the middle portionsthereof. Especially, in the case of the invention, the radius ofcurvature Ro of the outer raceway 18 a is set for a value 0.56 times thediameter Da of each of the rolling elements 17 (Ro≧0.56Da). Also, theradius of curvature Ri of the inner raceway 19 b is also set for a value0.56 times the diameter Da of each of the rolling elements 17(Ro≧0.56Da). On the other hand, in the case of the conventional pulleysupporting radial ball bearing, the radius of curvature of each of theouter and inner raceways is set for a value smaller than a value 0.56times the diameter of each of the rolling elements and, generally, it isset for a value about 0.52 times the diameter of each rolling element.

When the composing elements of the present embodiment are formed in theabove-mentioned manner, the two raceways 18 a, 19 b can be contactedwith the rolling surfaces of the rolling elements respectively at twopoints, that is, at a total of four points for each rolling element 17.In the case of the present embodiment, the positions of the rollingcontact portions between the two raceways 18 a, 19 a and the rollingsurfaces of the rolling elements 17 are expressed as rest angles θ, thatis, the angles that are shifted from the centers of the respectiveraceways 18 a, 19 b; and, the rest angles θ are respectively set for 20degrees. Also, in a state where the radial ball bearing 14 b isstructured by combining together the outer ring 15 a and inner ring 16 bwith the two or more rolling elements 17, in the radial ball bearing 14b, there exists a positive or negative radial clearance; and, even whenthe positive clearance exists, the value thereof is restricted to 0.2%or less of the pitch circle diameter Dp of the radial ball bearing 14 b.

Also, as shown in FIG. 2, to securing grooves 20, 20 which arerespectively formed in the inner peripheral surfaces of the two endportions of the outer ring 15 a, there are secured the outer peripheraledge portions of seal rings 21, 21, respectively. The seal rings 21, 21are structured in such a manner that elastic members 23 are respectivelyreinforced with core metals 22, while the outer peripheral edges of theelastic members 23 are elastically engaged with the securing grooves 20,20. In this state, the leading end edges of seal lips 24 disposed on theinner peripheral edge portions of the elastic members 23 are slidablycontacted with a portion of the inner ring 16 b over the entireperiphery thereof to thereby seal off the opening portions of the twoend portions of an internal space 25 in which the rolling elements 17are disposed. By the way, as the elastic members 23 which constitute theseal rings 21, 21, preferably, there may be used nitrile rubber oracrylic rubber.

And, grease (not shown) is charged into the internal space 25 that issealed off from an external space in this manner. Also, in the case ofthe present embodiment, the respective rolling elements 17 are rotatablyheld by a crown-type retainer 26. This retainer 26 is formed as anintegral body by injection molding synthetic resin such as polyamideresin or polyphenylene sulfide containing therein 5-35 weight percent(preferably, 10-25 weight percent) of glass fibers as reinforcingmaterial. The axial-direction thickness T₂₇ of the bottom portion ofthis retainer 26 (that is, the portion of the retainer 26 that is thethinnest in the circular-ring-shaped rim portion 27 and corresponds tothe deep portion of a pocket 28) is set for 10-40% of the diameter Da ofthe respective rolling elements 17 {T₂₇=(0.1-0.4)Da}. By restricting thefactors of the retainer 26 in this manner, while preventing an increasein the axial-direction dimension of the retainer 26, the strength of theretainer 26 can be secured and thus, regardless of a centrifugal forceapplied to the retainer 26 when the driven pulley 4 b is in high-speedrotation, the elastic deformation of the retainer 26 can be controlleddown to such degree that can prevent occurrence of any practicalproblem.

The radial ball bearing 14 b having the above-mentioned structure, asshown in FIG. 1, is assembled into between the inner peripheral surfaceof the driven pulley 4 b and the support tube part 3 of the casing 2 tothereby constitute a pulley rotation support apparatus for a compressor.In case where a pulley rotation support apparatus for a compressor isstructured in this manner, the width-direction central position (in FIG.1, a chained line α) of an endless belt 11 to be disposed on the outerperipheral surface of the above driven pulley 4 b is shifted from thewidth-direction central position of the above radial ball bearing 14 b(that is, the central position of the rolling element 17 shown by achained line β in FIG. 1) by δ (an offset quantity) in the axialdirection (in FIG. 1, in the right and left direction). In the case ofthe pulley rotation support apparatus according to the invention, theoffset quantity δ is set as 40% or less of the pitch circle diameter Dp(FIG. 2) of the radial ball bearing 14 b (0.4Dp≧δ). By the way,preferably, the offset quantity 6 may be set as 20% or less of the pitchcircle diameter (0.2Dp≧δ), more preferably, may be set 10% or less(0.1Dp≧δ), which makes it possible to secure the durability of theradial ball bearing 14 b.

This will be described below with reference to FIG. 3 which shows theresults of a test conducted by the present inventors. FIG. 3 is adiagrammatic view of the results of an endurance test conducted in orderto know the influence of the ratio of the offset quantity δ of theoperation position of a radial load with respect to the center of theradial ball bearing 14 b to the pitch circle diameter Dp of the two ormore rolling elements 17 constituting the radial ball bearing 14 b onthe life of the radial ball bearing 14 b. In FIG. 3, the horizontal axisthereof expresses the ratio (%) of the offset quantity δ and pitchcircle diameter Dp, while the vertical axis expresses the life ratio (adimensionless number). Also, in the case of the life ratio expressed inthe vertical axis, 1 expresses the life that is practically necessary.That is, in case where the life ratio is equal to or more than 1, therecan be provided a structure which can withstand practical use; and, incase where the life ratio is less than 1, the structure is not able towith stand practical use. By the way, this life ratio was obtained inthe following manner: that is, in a state that the inner ring 16 b wasfixed and the outer ring 15 a was rotating, the radial ball bearing 14 bwas operated under the following conditions.

-   -   Rotation speed: 10000 min⁻¹    -   Temperature: Normal temperature    -   Radial load: 2254N

The present inventors caused the offset quantity δ to vary in a total offive manners in the range of 11.5%-46% and measured the lives(durability) of the radial ball bearing in the respective five cases,using two or more samples for each case. The results of the test areshown by a broken line a in FIG. 3. By the way, in the intermediateportion of the broken line a of FIG. 3, line segments shown in theportions which respectively correspond to the above-mentioned five kindsof offset quantities δ respectively express the ranges of the variationsof the test results regarding the above-mentioned two or more samplesfor each case, while black points on the respective line segmentsrespectively express the means values thereof. As can be clearly seenfrom FIG. 3 which shows such test results, in case where the offsetquantity δ is restricted to 40% or less of the pitch circle diameter Dpof the radial ball bearing 14 b, there can be realized a structure whichis able to secure a practically necessary life and withstand practicaluse. On the other hand, in case where the offset quantity δ exceeds 40%of the pitch circle diameter Dp of the radial ball bearing 14 b, thedurability of the radial ball bearing 14 b is lowered suddenly. Also, incase where the offset quantity δ is restricted to 20% or less of theabove-mentioned pitch circle diameter, for the life of the radial ballbearing 14 b, there can be secured a value eight times the value that isnecessary for practical use. Further, in case where the offset quantityδ is restricted to 10% or less of the above-mentioned pitch circlediameter, for the life of the radial ball bearing 14 b, there can besecured a value ten times the value that is necessary for practical use.

When the above-mentioned compressor pulley rotation support apparatus isin use, the moment load proportional to the offset quantity δ is appliedthrough the driven pulley 4 b to the radial ball bearing 14 b due to thetension of the endless belt 11. And, the center axes of the outer ring15 a and inner ring 16 b respectively constituting the radial ballbearing 14 b tend to be incongruous with each other (to be inclined withrespect to each other). However, according to the invention, even inthis case, the center axes of the outer ring 15 a and inner ring 16 bcan be prevented from being incongruous with each other.

That is, since the radial clearance of the radial ball bearing 14 b whenit exists alone is restricted to 0.2% or less of the pitch circlediameter Dp of the radial ball bearing 14 b, the above-mentioned twoaxes are difficult to shift from each other. Also, because the offsetquantity δ of the winding position of the endless belt 11 with respectto the radial ball bearing 14 b is restricted to 40% or less of thepitch circle diameter Dp, preferably, to 20% or less, more preferably,to 10% or less, the moment load to be applied through the driven pulley4 b to the outer ring 15 a can be controlled down to a small value. Forthese reasons, the inclination of the driven pulley 4 b and outer ring15 a with respect to the inner ring 16 b can be controlled and thus anexcessively large surface pressure can be prevented from acting onto therolling contact portion of the radial ball bearing 14 b, thereby beingable to secure the durability of the radial ball bearing 14 b. Also, thepartial wear of the endless belt 11 arranged on the driven pulley 4 bcan be reduced, thereby being able to secure the durability of theendless belt 11.

By the way, in order to eliminate the above-mentioned moment load thatgives rise to the occurrence of the mutual deviation between theabove-mentioned two axes, there may be employed the idea that the offsetquantity δ is set for zero; that is, the axial-direction centralposition α of the winding position of the endless belt 11 on the outerperipheral surface of the driven pulley 4 b is made to coincide with theaxial-direction central position β of the radial ball bearing 14 b.However, in this case, wear and heat generation, which are caused byslippage at the contact points between the rolling surfaces of therolling elements 17 and the outer ring and inner raceways 18 a, 19 b,are easy to increase. That is, in case where the offset quantity δ isset for zero in order to eliminate the moment load, the surfacepressures of the contact points, namely, two contact points for eachrolling element 17 and thus a total of four points existing between therolling surfaces of the rolling elements 17 and the outer ring and innerraceways 18 a, 19 b, are substantially equal on the axial-direction twosides. In this state, in case where the driven pulley 4 b is rotated,the slippage at the respective contact points is easy to increase, sothat the rotation resistance of the radial ball bearing 14 b is easy toincrease and thus the heat generation is easy to increase. And, as theresult of the heat generation and the like, there is a possibility thatthe rolling fatigue life of the radial ball bearing 14 b can be lowered.In view of this, when enforcing the invention, in consideration of suchcircumstances, the minimum value of the offset quantity δ may also beset for 1 mm or more (δ≧1 mm). By setting the minimum value of theoffset quantity δ for 1 mm or larger, there can be provided a differencebetween the surface pressures of the contact points on theaxial-direction two sides, which not only can prevent the occurrence oflarge slippage at the respective contact points to thereby prevent therotation resistance of the radial ball bearing 14 b from increasing, butalso can extend the rolling fatigue life of the radial ball bearing 14 bfurther.

Also, according to the invention, the radii of curvature Ri, Ro of theinner raceway 19 b and outer raceway 18 a are set 0.56 times thediameter Da of the rolling elements 17 or more (Ri, Ro≧56Da). Thanks tothis, even when the invention is used a compressor which is an apparatusrequiring an increase in the rotation thereof, an increase in thecapacity thereof and a reduction in the size thereof, there can besecured sufficiently not only the seizure life of grease to be chargedinto the interior of the radial ball bearing 14 b but also the run-upallowance of the rolling elements 17.

According to a calculation made by the inventors of the invention, inthe case of the pulley rotation support apparatus of the invention, whencompared with a conventional apparatus in which the radii of the innerring and outer raceways are 0.55 times the diameter of the respectiverolling elements, a PV value having a great influence on the seizurelife of the grease can be reduced by 5% or more. Here, the PV value isthe product of the pressure P of the contact portion between the rollingsurfaces of the rolling elements 17 and the inner, outer raceways 19 b,18 a and the maximum slip speed V of the respective parts of the presentcontact ellipse. And, the pressure P increases as the ratios Ri/Da,Ro/Da of the radii of curvature Ri, Ro of the inner ring, outer raceways19 b, 18 a with respect to the diameter Da of the respective rollingelements 17 increase, whereas the maximum slip speed V decreases as theabove ratios Ri/Da, Ro/Da increase. And, because, when these ratiosRi/Da, Ro/Da are 0.56, the degree of the reduction in the above maximumslip speed has a great influence on the PV value, the PV value isreduced suddenly as described above. Further, according to a calculationmade by the inventors of the invention, when compared with theabove-mentioned conventional apparatus, the run-up allowance of therolling element 17 onto the shoulder can be enhanced by 12% or more.Thanks to these calculations, the effects of the invention can beconfirmed.

Also, the foregoing description has been given based on the embodimentof the invention using a four-point-contact-type radial ball bearing 14b in which the rolling surfaces of the rolling elements 17 are contactedwith the outer raceway 18 a and inner raceway 19 b respectively at twopoints, a total of four points, and the test results thereof. However,even in the case of such a three-point-contact-type radial ball bearing14 c as shown in FIG. 4 in which the rolling surface of a rollingelement 17 is contacted with an inner raceway 19 c formed in the outerperipheral surface of an inner ring 16 c at a point and the rollingsurface of the rolling element 17 is contacted with an outer raceway 18a formed in the inner peripheral surface of an outer ring 15 a at twopoints, in case where the embodiment is structured similarly to theabove case, similar effects can be obtained. The present inventorsconducted a test also on the above three-point-contact-type radial ballbearing 14 b and obtained the relationship between the offset quantityand the life ratio. The results of this test, together with those of thepreviously-described four-point-contact-type radial ball bearing 14 b,are shown by a solid b line in FIG. 3. In the intermediate portion ofthe solid line b of FIG. 3, vertical-direction line segments, which arerespectively shown in the portions corresponding to the above-mentionedfive kinds of offset quantities δ, express the ranges of variations inthe test results regarding to the three-point-contact-type radial ballbearing 14 b using two or more test samples for each case, whereas whitepoints on these line segments express the mean values of the respectivevariation ranges.

As can be seen clearly from FIG. 3 which shows the above-mentioned testresults, in the three-point-contact-type radial ball bearing 14 c aswell, in case where the offset quantity δ is restricted to 40% or lessof the pitch circle diameter Dp of the radial ball bearing 14 c, therecan be secured the life that is practically necessary, thereby beingable to realize a structure which can withstand practical use. On theother hand, in case where the offset quantity δ exceeds 40% of the pitchcircle diameter Dp of the radial ball bearing 14 c, the durability ofthe radial ball bearing 14 c is worsened suddenly. Also, in case wherethe offset quantity δ is restricted to 20% of or less than the pitchcircle diameter Dp of the radial ball bearing 14 c, the durability ofthe radial ball bearing 14 c can be enhanced up to a value which is 12times the practically necessary value or more. Further, in case wherethe offset quantity δ is restricted to 10% of or less than the pitchcircle diameter Dp of the radial ball bearing 14 c, the durability ofthe radial ball bearing 14 c can be enhanced up to a value which isabout 13 times the practically necessary value or more. As can be seenobviously from such FIG. 3, when the lives of the two kinds of radialball bearings are compared with each other, the life of thethree-point-contact-type radial ball bearing 14 c is longer than thelife of the four-point-contact-type radial ball bearing 14 b.

However, when a moment load is applied to driven pulleys respectivelysupported by these two rolling element bearings 14 c, 14 b, theinclination angle of the driven pulley supported by thethree-point-contact-type radial ball bearing 14 c is larger than theinclination angle of the driven pulley supported by thefour-point-contact-type radial ball bearing 14 b. Therefore, the life ofan endless belt arranged on the driven belt supported by thethree-point-contact-type radial ball bearing 14 c is shorter than thelife of an endless belt arranged on the driven belt supported by thefour-point-contact-type radial ball bearing 14 b. For this reason,actually, according to uses, while taking into account the balancebetween the lives of the endless belts of the radial ball bearings 14 c,14 b, one of the three-point-contact-type or four-point-contact-typeradial ball bearing 14 c, 14 b can be selected.

Also, a three-point-contact-type radial ball bearing is not limited tothe above-mentioned structure shown in FIG. 4 but, in the case of such athree-point-contact-type radial ball bearing 14 d as well as shown inFIG. 5 in which the rolling surface of a rolling element 17 is contactedwith an outer raceway 18 b formed in the inner peripheral surface of anouter ring 15 b at a point and the rolling surface of the rollingelement 17 is contacted with an inner raceway 19 b formed in the outerperipheral surface of an inner ring 16 b at two points, when theembodiment is structured similarly to the three-point-contact-typeradial ball bearing 14 c, there can be obtained similar effects.

The present embodiment is based on the Japanese patent application(Patent Application 2002-015428) filed on Jan. 24, 2002 and thus thecontents thereof are incorporated into the present embodiment forreference. Now, FIGS. 7 to 11 show a second embodiment according to themode for carrying out the invention, corresponding to Claim 1. By theway, the present embodiment is characterized in that the openingdirection of a pocket 44 of a retainer 45 used in a single-row ballbearing 40 is set to thereby decide a direction in which a radial load Fis applied to a bearing central line β, and the radial load F offsetwith respect to the bearing central line β is applied to thereby allowgrease existing around the periphery of the load area during theoperation of the bearing to circulate actively from an inner raceway onthe opening side of the pocket 44 of the retainer 45 to an outerraceway.

The single-row ball bearing 40 according to the second embodiment is afour-point-contact-type ball bearing with its inner and outer rings eachhaving a Gothic-arch-like shape; and it comprises an inner ring 41, anouter ring 42, two or more balls (rolling elements) 43 interposedbetween the inner ring 41 and outer ring 42, a crown-type retainer(which is hereinafter referred to as a retainer) 45 for holding the twoor more balls 43 at regular intervals in the peripheral directionthereof, and a pair of seal members (seal plates) 46, 46 disposed on theaxial-direction two sides of each of the balls 43.

Also, in the outside diameter surface of the inner ring 41, there areformed a first groove 41 a providing a first contact point with the ball43 and a second groove 41 b providing a second contact point with theball 43, thereby forming an inner raceway. And, in the inside-diametersurface of the outer ring 42 as well, there are formed a first groove 42a providing a first contact point with respect to the balls 43 and asecond groove 42 b providing a second contact point with respect to theballs 43, thereby forming an outer raceway.

The shape of the section of the inner raceway is formed as aGothic-arch-like shape to be contacted with the ball 43 at a given restangle, and this shape is symmetric with respect to the axial-directioncentral line β of the bearing. The radius of curvature of the firstgroove 41 a of the inner ring 41 is equal to the radius of curvature ofthe second groove 41 b thereof.

Also, the shape of the section of the outer raceway is formed as aGothic-arch-like shape to be contacted with the ball 43 at a given restangle, and this shape is symmetric with respect to the axial-directioncentral line β of the bearing. The radius of curvature of the firstgroove 42 a of the outer ring 42 is equal to the radius of curvature ofthe second groove 42 b thereof.

The retainer 45 is structured such that, on a retainer main body portion47 having a circular-ring shape, there are formed two or more pockets 44at regular intervals in the circumferential direction thereof throughpillar portions. Since the single-row ball bearing 40 is used when theradial load F is applied to the axial-direction central line β of thebearing toward the right middle side in FIG. 7, the opening of thepocket 44 of the retainer 45 is formed so as to face in the directionwhere the radial load F is applied.

The seal member 46 is formed such that a core metal 46 a composedserving as a core member is covered with rubber 46 b made of elasticmaterial. The seal member 46 is a member which is mounted on the outerring 42 after the balls 43 are mounted between the inner and outerrings, and it is of a contact type that the leading end portion thereofcan be contacted with the inner ring 41.

And, grease serving as a lubricant is charged into a bearing spaceenclosed by the pair of seal members 46, 46.

In the single-row ball bearing 40, the opening side of the pocket 44 ofthe retainer 45 is displaced so as to face in the direction where theradial load F is applied; however, in the assembled state of thebearing, since the existence of the seal member 46 makes it difficult toconfirm the assembling direction of the retainer 45, it is necessary tobe able to confirm the assembling direction of the retainer 45 from theouter appearance of the bearing.

That is, as shown in FIG. 8, signs 48 serving as marks showing theopening side of the pocket 44 of the pocket 44 of the retainer 45 areapplied to the end faces (front surfaces) of the inner ring 41 and outerring 42 that are disposed on the opening side of the pocket 44. Thus,even when the bearing 40 is held in the assembled state thereof, theopening side of the pocket 44 of the retainer 45 can be confirmed simplyand instantaneously, which can positively eliminate the wrongconfirmation of the assembling direction of the bearing.

By the way, the sings 48 may also be applied to the end faces of theinner ring 41 and outer ring 42 that are disposed on the counter-openingside of the pocket 44 of the retainer 45 disposed on the opposite sideto FIG. 8. In this case, the side, to which the marks 48 are applied,shows the assembling start position side of the retainer 45, while theside with no marks 48 applied thereto shows the opening side of thepocket 44 of the retainer 45 necessarily.

Also, the marks 48 shown in FIG. 8 are simply an example and the marksare not limited to them, that is, they can be selected arbitrarily. Forexample, a seal-like member produced separately may be bonded to the endface, or the end face may be directly carved. Further, the mark may alsobe formed in a plane manner or in a projecting manner, while the numberand position of the marks may be selected arbitrarily.

Also, the mark 48 may also be applied to one of the end faces of theinner ring 41 and outer ring 42. And, the mark 48 may also be applied tothe seal member 46 which is opposed to the opening side or back surfaceside of the pocket 44 of the retainer 45.

Also, as the mark, the colors or materials of the seal members 46 may bechanged to thereby vary the structures of the bearing-one-end-side andthe other-end-side seal members from each other. For example, the colorsor patterns of the two seal members 46 may be different from each other.

Further, uneven portions such as notches may be formed in one or both ofthe axial-direction end edge portions of the inner ring 41 and outerring 42 to thereby distinguish from each other.

According to the thus-structured single-row ball bearing 40, in casewhere, while it is in operation, the radial load F is applied to theaxial-direction central line β of the bearing on the right side in FIG.7, the outer ring 42 is inclined due to the radial load F. As the outerring 42 is inclined, the ball 43 is contacted with the inner and outerrings with a certain contact angle, so that grease poured into thesecond groove 42 b of the outer raceway is moved to the counter-contactside where a clearance between the ball 43 and raceway groove is wide.

At the then time, in the bearing space on the opening side of the pocket44, the grease existing in the first groove 42 b, as shown by b in FIG.7, piles up on the outer ring shoulder portion 42 c and then, due to therotation of the ball 43 on its own axis, it moves toward the innerraceway.

On the other hand, in the bearing space existing on the counter-openingside of the pocket 44, grease existing in the first groove 41 a of theinner raceway shown by a in FIG. 7, as shown by c in FIG. 7, accumulateson the inner ring shoulder 41 c and, when it is moved toward the outerraceway due to the rotation of the ball 43 on its own axis, as shown byd in FIG. 7, it is scraped by the edge portion of the pocket 44 of theretainer 45 and piles up on the inside diameter portion of the retainer45.

And, the grease piled up on the inside diameter portion of the retainer45 and shown by d in FIG. 7, as shown by e in FIG. 7, moves into theinterior of the pocket 44 of the retainer 45 and, at the same time, dueto a centrifugal force generated by the rotation of the retainer 45, thegrease moves from the outside diameter portion of the retainer 45 to thefirst groove 42 a of the outer raceway along the end face of theretainer main body 47 of the retainer 45.

Thanks to this, while the bearing is in operation, the grease existingaround the load area is circulated from the inner raceway on the pocket44 opening side of the retainer 45 to the outer raceway. As a result ofthis, much grease flows into the inner raceway and outer raceway tothereby realize the active circulation of the grease.

By the way, in the case of the grease existing around the no-load area,since the contact surface pressure between the ball 43 and outer racewayand inner raceway is small and thus they are little contacted with eachother, they have only a small influence on the seizure of the grease.

As described above, in the single-row ball bearing 40 according to thesecond embodiment, since the opening of the pocket 44 of the retainer 45is disposed so as to face in the direction where the radial load F isapplied to the bearing center line β, in case where the radial load Foffset with respect to the bearing center line β is applied, during theoperation of the bearing, the grease existing around the load area isactively circulated from the inner raceway on the opening side of thepocket 44 of the retainer 45 to the outer raceway.

Therefore, when the bearing receives the offset load, the bearingseizure life can be extended and thus the bearing performance can beenhanced.

Also, because the marks 48 showing the direction of the opening of thepocket 44 of the retainer 45 are applied to the inner ring 41 and outerring 42 of the inner ring 41, outer ring 42 and seal members 46, whenassembling the single-row ball bearing 40, there is no possibility thatthe direction of the opening of the pocket 44 of the retainer 45 can bemistaken, so that the assembling operation allowing the single-row ballbearing 40 to fulfill the performance thereof can be carried out verysimply.

Next, as a comparative example for the second embodiment, there is takenan example in which the assembling direction of the retainer 45 isreversed and the comparative example will be described below withreference to FIG. 9. By the way, in the present comparative example,parts thereof having similar structures and operations to those thathave been already described are given the same designations orequivalent designations in FIG. 9 and thus the description thereof issimplified or omitted here.

As shown in FIG. 9, in a single-row ball bearing 50, a retainer mainbody 47 situated on the back surface of the retainer 45 is disposed onthe side where the radial load F on the right side in FIG. 9 is appliedto the axial-direction center line β of the bearing.

In the single-row ball bearing 50 according to the comparative example,in case where, during the operation of the bearing, the radial load F isapplied to the axial-direction center line β of the bearing on the rightside in FIG. 9, the outer ring 42 is inclined due to the radial load F.As the outer ring 42 is inclined, the ball 43 is contacted with theinner and outer rings with a certain contact angle, so that greasepoured into the inner raceway and outer raceway is moved to thecounter-contact side where a clearance between the ball 43 and racewaygroove is wide.

At the then time, in the bearing space on the opening side of the pocket44, the grease of the first groove 41 a of the inner raceway shown by ain FIG. 9, as shown by b in FIG. 9, accumulates on the inner ringshoulder portion 41 c and is then moved to the outer raceway due to therotation of the ball 43 on its own axis.

On the other hand, in the bearing space on the retainer main body 47side which is the back surface side of the pocket 44, the grease of thesecond groove 42 b of the outer raceway shown by a in FIG. 9, as shownby c in FIG. 9, accumulates on the outer ring shoulder portion 42 c andis going to move toward the inner raceway due to the rotation of theball 43 on its own axis; however, as shown by d in FIG. 9, the grease isscraped off by the edge portion of the pocket 44 of the retainer 45 andthus it accumulates on the outside diameter portion of the retainer 45.

And, the grease, which accumulates on the outside diameter portion ofthe retainer 45 and is shown by d in FIG. 9, as shown by e in FIG. 9,moves into the interior of the pocket 44 of the retainer 45, or, due toa centrifugal force generated by the rotation of the retainer 45, thegrease is returned again to the outer raceway shown by a in FIG. 9.

In this manner, when the retainer main body 47 situated on the backsurface of the retainer 45 is disposed on the side where the radial loadF is applied to the axial-direction center line β of the bearing, duringthe operation of the bearing, the grease existing in the second groove42 b of the outer raceway on the retainer main body 47 side, which isthe counter-opening side of the pocket 44 of the retainer 45, does notmove from the outer raceway to the inner raceway but stagnates aroundthe outer raceway.

Next, FIG. 10 shows the results of a high temperature and high speeddurability test conducted using the single-row ball bearing 40 accordingto the second embodiment.

The test was conducted under the following conditions.

-   -   Outer ring rotation: 10,000 r/min    -   Moment load: 7,000˜10,000 N·mm.

Evaluation was carried out using a combination of the following threekinds of specifications.

-   -   Specification 1: Grease A (Ether group)    -   Specification 2: Grease B (Ether group+Polyalphaolein group)    -   Specification 3: Grease C (Ether group+Polyalphaolein        group+Ester group)

The results of the above test show that the specification 1 provides avalue 1.22 times, specification 2 provides a value 2.26 times andspecification 3 provides a value 1.28 times. That is, it is found thatthe specification, in which the opening of the pocket 44 of the retainer45 is disposed such that the radial load F direction faces the bearingcentral line β, can withstand long-time use. Especially, when the greaseB according to the specification 2 is used, it is found that it canprovide an outstanding effect.

By the way, the second embodiment is not limited to the above-mentionedstructure but it can be deformed or improved properly. For example, thepresent embodiment is not limited to the four-point-contact ball bearingused as the single-row ball bearing, but, also when a deep-groove ballbearing, an angular ball bearing, or a three-point-contact ball bearingis used, there can be obtained a similar effect to the above-mentionedcase.

Also, the kinds of the components or the like of the grease, the shapeand material of the pocket of the retainer, the shape, material and thelike of the seal member are not limited to the above-mentioned ones atall.

The single-row ball bearing 40 according to the second embodiment canalso be applied to, for example, the pulley 61 of an electromagneticclutch 60 for a car air conditioner compressor shown in FIG. 11. Thiselectromagnetic clutch 60 is used to transmit the rotation powergenerated by an engine to a compressor disposed in a refrigerating cyclefor a car air conditioner or cut off the rotation power.

In the case of the electromagnetic clutch 60, a rotary disk 64 isdisposed on the leading end portion of a drive shaft 63 which projectsrotatably from the center of a compressor housing 62 and, on the outerperiphery side of the rotary disk 64, there is mounted an armature 65through a flexible member 65. A cylindrical shaft 67 is disposedintegrally with and projectingly from the compressor housing 62 in sucha manner that it encloses the periphery of the drive shaft 63, and theinner ring 41 of the single-row ball bearing 40 is fitted with theoutside of the outer peripheral surface of the cylindrical shaft 67.

A rotor 68 is fitted with the outer surface of the outer ring 42 of thesingle-row ball bearing 40 and a driven pulley 69 is formed integrallywith the outer peripheral surface of the rotor 68. An endless belt 70shown by an imaginary line is displaced on the outer peripheral surfaceof the driven pulley 69. Also, on the side surface of the rotor 68 onthe opposite side to the compressor housing 62, there is formed afriction surface 71 which transmits the rotation power due to a frictionforce generated when it is contacted with the armature 66.

A recessed portion 72 is formed in the side surface of the rotor 68 onthe compressor housing 62 side. In to the recessed portion 72, there canbe stored an electromagnetic coil 73 in such a manner that it is notcontacted with the rotor 68. The electromagnetic coil 73 is fixed to thecompressor housing 62.

The single-row ball bearing 40 is assembled between the rotor 68 anddriven pulley 69 in such a manner that the center of the radial load F,which is the width-direction center position α of the endless belt 70,is situated at a position shifted by an offset quantity L1 with respectto the bearing center line β; and, the opening of the pocket 44 of theretainer 45 is disposed so as to face in the direction where the radialload F is applied to the bearing center line β.

In the thus-structured electromagnetic clutch 60 for a car airconditioner compressor, when the electromagnetic coil 73 is notenergized, the friction surface 71 is disposed in such a manner that ithas a clearance with respect to the armature 66. And, in case where acurrent is allowed to flow in the electromagnetic coil 73, there isgenerated a magnetic field and, due to its magnetic field, the armature66 is attracted toward the electromagnetic coil 73 against the elasticforce of the flexible member 65 and is thereby pressure contacted withthe friction surface 71. Thanks to this, the rotation power of thepulley 61 is transmitted to the compressor through the armature 66,rotary disk 64 and drive shaft 63, thereby driving the compressor.

The second embodiment disclosed in the present patent application isbased on the Japanese Patent Application (Patent Application2002-174268) filed on Jun. 14, 2002 and thus the contents of the presentapplication are taken into the second embodiment for reference.

Now, FIGS. 12 and 13 show a third embodiment of the mode for carryingout the invention. By the way, the present embodiment is characterizedby an improvement in the shape of a seal plate 91 a which allows greasecharged into the space 92 of a rolling bearing 81 a with a seal plate tocirculate within the space 92 to thereby delay the degradation of thegrease used to lubricate the rolling contact portions of an innerraceway 82 and outer raceway 84 with the rolling surfaces of therespective rolling elements 86.

Of the inner surfaces of the seal plate 91 a constituting the rollingbearing 81 a with a seal plate according to the present embodiment, thenear-to-outside-diameter portion close to the inner peripheral surfaceof an outer ring 85 (which exists in the portion of the inner surface ofthe seal plate 91 a slightly nearer to the inside diameter portion thanthe inner peripheral surface of the outer ring) is formed as anoutside-diameter-side inclined surface 98 which is inclined inwardly inthe axial direction as it goes outwardly in the diameter directionthereof and also which corresponds to in inclined surface as set forthin Claim 3. This outside-diameter-side inclined surface 98 can be formedof a portion of an elastic member 94 a constituting the above seal plate91 in the following manner: that is, the inner surface of such portionof the elastic member 94 a that is situated near to the outside-diameterportion of the seal plate 91 a is inclined inwardly as it goes outwardlyin the diameter direction thereof. Also, a flat surface 108 existing onthe periphery of the above outside-diameter-side inclined surface 98 iscontacted with the entire periphery of the outer surface 109 of ashoulder portion 99 existing between the outer raceway 84 and a securinggroove 90. Therefore, the outer peripheral edge of theoutside-diameter-side inclined surface 98 is contacted with or is closeto the outer edge of the outer peripheral surface of the above shoulderportion 99. By the way, the continuing portions between the innerperipheral surfaces of the above shoulder portions 99 and the outerraceway 84 are formed as chamfer portions 100, which makes it difficultfor the respective rolling elements 86 to run up onto the shoulderportions 99. This chamfer portion 100 is chamfered, for example, by 0.02mm or larger, or, is formed as a projectingly curved surface in whichthe radius of curvature of the section shape is 0.02 mm or larger.

Also, according to the present embodiment, the inclination angle α withrespect to the axial direction of the above outside-diameter-sideinclined surface 98 is set for an angle of 30° or larger, thereby makingit possible for the grease charged into the space 92 to circulate moreefficiently. The reason why the inclination angle α is set for 30° orlarger will be explained with reference to the following table 1. TABLE1 Ratio of Force F acting Inclination on grease to Centrifugal AngleForce F_(r) α (°) F/F_(r) (%) 10 17 20 34 30 50 50 77 90 100

This table 1 shows a ratio of a force, which varies according the aboveinclination angle α and acts on grease existing on the aboveoutside-diameter-side inclined surface 98, to the centrifugal forceF_(r) in %. That is, as can be seen clearly from FIG. 13, since theforce F acting on the grease acts in parallel to the aboveoutside-diameter-side inclined surface 98, this force F can be expressedby the following equation.F=F _(r) sin α

Therefore, from the above equation, there can be obtained the abovetable 1. As can be seen clearly from this table 1, assuming that theabove inclination angle α is 30° or more (α≧30°), the force F acting onthe grease existing on the above outside-diameter-side inclined surface18 is 50% or more of the above-mentioned centrifugal force F_(r)(F≧0.5F_(r)), the grease flowing on the outside-diameter-side inclinedsurface 98 is easy to flow outwardly in the diameter direction. By theway, as the inclination angle α is increased, the grease is easier toflow; and, with the shape, size and the like of the retainer 87 takeninto account, the inclination angle α is decided in such a manner thatthe grease cannot be checked between the above outside-diameter-sideinclined surface 98 and retainer 87 (in such a manner that a clearance110 between the outside-diameter-side inclined surface 98 and retainer87 cannot be narrowed too much). Generally, it is believed to be properthat the upper limit of the above inclination angle is about 50° (up to60°).

Also, according to the present embodiment, of the inner surfaces of theabove seal plate 91 a, the inner surface of the near-to-inside-diameterportion is formed as an inside-diameter-side inclined surface 101 whichis inclined outwardly in the axial direction thereof as it goesoutwardly in the diameter direction thereof; and, the inner peripheraledge neighboring portion of the inside-diameter-side inclined surface101 is slidably contacted with or is adjacently opposed to thenear-to-outside-diameter portions of the outer surfaces of two shoulderportions 102 respectively formed on the axial-direction two sides of aninner raceway 82 formed in the outer peripheral surface of the innerring 83 over the entire periphery thereof. Thanks to this, the grease,which is pushed out from the inner raceway 82 to the outer peripheralsurface of the shoulder portion 102, is easy to adhere to the innersurface of the above seal plate 91 a. Also, similarly to the abovegrease existing on the above outside-diameter-side inclined surface 98,a centrifugal force acts on the grease adhered to the aboveinside-diameter-side inclined surface 101, and the grease adhered tothis inside-diameter-side inclined surface 101 is easy to be sentoutwardly in the diameter direction thereof. By the way, in case wherethe inclination angle of the above inside-diameter-side inclined surface101 with respect to the axial direction is set for 30° or larger,similarly to the above outside-diameter-side inclined surface 98, of thecentrifugal force, the rate of a component thereof acting on the greaseadhered to the above inside-diameter-side inclined surface 101increases, so that the grease adhered to this inside-diameter-sideinclined surface 101 can be sent to the outside diameter side moreeasily.

According to the above-structured rolling bearing 81 a with a seal plateof the present embodiment, there can be eliminated the possibility thata large quantity of grease can stay on the inner surfaces of the sealplate 91 a; and thus the grease charged into the spaces 92 respectivelyexisting between the above-mentioned outer raceway 84 and inner raceway82 and formed in the respective rolling elements 86 can be circulatedsmoothly including the above-mentioned rolling contact portions. Thatis, since, of the inner surfaces of the above seal plate 91 a, thenear-to-outside-diameter portion is formed as the outside-diameter-sideinclined surface 98 which is inclined inwardly in the axial direction asit goes outwardly in the diameter direction, the grease, which hasadhered to the inner surface of the above seal plate 91 a and has beenmoved to the outside diameter side of the above seal plate 91 a due tothe centrifugal force, is introduced into the above outer raceway 84through the inner peripheral surfaces of the above shoulder portions 99.Thanks to this, there is eliminated a fear that a large quantity ofgrease can collect on the inner surfaces of the seal plate 91 a and,therefore, the grease charged into the spaces 92 can be circulated withgood efficiency including the above-mentioned rolling contact portions.Due to this, most of the grease charged into the above spaces 92 can beused sequentially for lubrication of the above rolling contact portions.This can further delay the degradation of the grease that is used tolubricate these rolling contact portions.

Especially, in case where the inclination angle of the aboveoutside-diameter-side inclined surface 98 to the axial direction is setfor 30° or larger, the grease moved along the inner surfaces of the sealplate 91 a can be guided to the outer raceway 84 more efficiently. Thatis, as described above, since, when the inclination angle of the aboveoutside-diameter-side inclined surface 98 is increased, a centrifugalforce acting on the grease existing on this outside-diameter-sideinclined surface 98 is increased, this grease can be guided to the outerraceway 84 side with good efficiency, so that prevention of thedegradation of the grease due to the circulation of the grease can berealized more effectively.

Next, FIG. 14 shows a fourth embodiment of the mode for carrying out theinvention, corresponding to Claim 2. According to the presentembodiment, the inner surfaces of a seal plate 91 b are composed of theinclined surfaces 105 of the diameter-direction middle portion thereof,the outside-diameter-side concavely curved surfaces 103 of thenear-to-outside-diameter portions thereof, and the inside-diameter-sideconcavely curved surfaces 106 of the near-to-inside-diameter portionsthereof. Of these surfaces, the inclined surfaces 105 are formed in sucha manner that their associated core metals 93 are respectively inclinedinwardly in the axial direction thereof as they go from thenear-to-inside-diameter portions of the middle portion outwardly in thediameter direction, and the inner surfaces of the thus-inclined portionsare used as the inclined surfaces 105. Also, the aboveoutside-diameter-side concavely curved surfaces 103 are surfaces whichare respectively formed in the outside-diameter-side portions of theabove inclined surfaces 105, correspond to concavely curved surfaces asset forth in Claim 3, and are curved inwardly in the axial direction asthey go outwardly in the diameter direction. Also, the aboveinside-diameter-side concavely curved surfaces 106 are disposed in theinside-diameter-side portions of the inner surfaces of the above sealplate 91 b and are curved outwardly in the axial direction as they gooutwardly in the diameter direction. The inner peripheral edge portionof each of the inside-diameter-side concavely curved surfaces 106 isslidably contacted with or adjacently opposed to thenear-to-outside-diameter portion of its associated outer surface 111 ofthe shoulder portion 102 of the inner ring 83, while the outerperipheral edge portion thereof is extended up to the middle portion ofthe above seal plate 91 b. That is, in the case of the inner surfaces ofthe above seal plate 91 b, the outside-diameter-side andinside-diameter-side portions thereof are formed as the above-mentionedtwo outside-diameter-side and inside-diameter-side concavely curvedsurfaces 103, 106 which are produced by forming concavely curvedsurfaces respectively in the inner surfaces of elastic members 94 b, andthe middle portions of the inner surfaces of the seal plate 91 b areformed as the above inclined surfaces 105 that can be obtained byinclining the above core metals 93 a; and, the respective surfaces 103,106 and 105 are connected together continuously and smoothly to therebystructure the inner surfaces of the seal plate 91 b.

Also, in the present embodiment, the retainer 87 a holding therespective rolling elements 86 has such a shape that can prevent theretainer 87 a from interfering with the inner surfaces of the seal plate91 b. That is, the outer surface (in FIG. 12, the right side surface) ofa rim portion 88 formed on the axial-direction one end side (in FIG. 12,on the right side) of the retainer 87 a has a shape matched to the shapeof the inner surface of the seal plate 91 b to which the present outersurface is opposed. By the way, in the case of the illustratedembodiment, in order that, when the grease moves outwardly in thediameter direction on the inner surface of the above seal plate 91 b,the flow of the grease cannot be retarded by the above rim portion 88,there is secured a clearance δ of 0.7 mm or more between the outersurface of this rim portion 88 and the inner surface of the above sealplate 91 a.

Also, in the case of the present embodiment, of the inner surfaces ofthe above seal plate 91 b, the near-to-outside-diameter portion thereofis formed as the above outside-diameter-side concavely curved surface103 instead of the outside-diameter-side inclined surface 98 previouslydescribed with reference to FIG. 12. This outside-diameter-sideconcavely curved surface 103, similarly to the outside-diameter-sideinclined surface 98, is also be able to guide the grease to theabove-mentioned outer raceway 84. By the way, in the case of the aboveoutside-diameter-side concavely curved surface 103, by increasing theradius of curvature thereof, the grease sent outwardly in the diameterdirection along the inner surfaces of the seal plate 91 b can be guidedto the outer raceway 84 with more efficiency. Also, in the case of thepresent embodiment, since an inside-diameter-side concavely curvedsurface 106 is formed in the inside-diameter-side inner surface of eachof the seal plates 91 b and an inclined surface 105 is formed in theinner surface of the middle portion thereof as well as these surfaces106, 105 are connected continuously with the above-mentionedoutside-diameter-side concavely curved surface 103 smoothly, the greasepushed out from the inner raceway 82 to the outer peripheral surface ofthe shoulder portion 102 can be guided more easily. By the way, theabove-mentioned outside-diameter-side concavely curved surface 103 andinside-diameter-side concavely curved surface 106 can be respectivelyformed of a single curved surface or a composite curved surface composedof two or more curved surfaces connected together continuously andsmoothly. The remaining structures and operations of the presentembodiments are similar to those of the previously described thirdembodiment.

Next, FIG. 15 shows a fifth embodiment of the mode for carrying out theinvention, corresponding to Claim 2. According to the presentembodiment, an elastic member 94 c is disposed on the entire area of theinner surface of a core metal 93 constituting a seal plate 91 c, anoutside-diameter-side concavely curved surface 103 is formed in theoutside-diameter-side inner surface of the elastic member 94 c, aninside-diameter-side concavely curved surface 106 is formed in theinside-diameter-side inner surface thereof respectively, while theseconcavely curved surfaces 103 a, 106 are continuously connected witheach other smoothly. That is, in the present embodiment, differentlyfrom the above-mentioned fourth embodiment, no inclined surface isformed in the inner surface of the middle portion of the seal plate, butthe entire inner surface of the seal plate is composed of a single,continuously and concavely curved surface. The remaining structures andoperations of the present embodiment are similar to those of theabove-mentioned fourth embodiment.

Next, FIG. 16 shows a sixth embodiment of the mode for carrying out theinvention, corresponding to Claim 2. In the case of the presentembodiment, in the structure according to the previously described thirdembodiment, the portions of the inner peripheral surface of the outerring 85 a that exist between the outer raceway 84 and securing grooves90, 90 are formed as curved surface portions 104, 104 which arerespectively curved toward the axial-direction two end edge portions ofthe outer raceway 84 as they go outwardly in the diameter direction.Each of the curved surface portions 104, 104 continues smoothly with itsassociated outside-diameter-side inclined surface 98 as well as thetangential direction of the portion thereof continuously connected withthe chamfer portion 100 extends substantially in parallel to the axialdirection. Thanks to this, not only grease, which has been sentoutwardly in the diameter direction along the above-mentionedoutside-diameter-side inclined surface 98, can be easily guided to theabove outer raceway 84, but also there can be formed the above chamferportion 100 which is used to prevent the rolling element 86 from runningup onto the above curved surface portion 104. The remaining structuresand operations of the present embodiment are similar to theabove-described third embodiment.

Next, FIG. 17 shows a seventh embodiment of the mode for carrying outthe invention, corresponding to Claim 2. In the case of the presentembodiment, there is employed a structure in which, in addition to thestructure according to the previously described fourth embodiment shownin FIG. 14, similarly to the above-described sixth embodiment shown inFIG. 16, curved surface portions 104, 104 are formed in the innerperipheral surface of the outer ring 85 a. The remaining structures andoperations of the present embodiments are similar to those of thepreviously described fourth and sixth embodiments.

Next, FIG. 18 shows an eighth embodiment of the mode for carrying outthe invention, corresponding to Claim 2. In the case of the presentembodiment, there is employed a structure in which, in addition to thestructure according to the previously described fifth embodiment shownin FIG. 15, similarly to the previously described sixth embodiment shownin FIG. 16, guide portions 104, 104 are respectively formed in the innerperipheral surface of an outer ring 85 a. The remaining structures andoperations of the present embodiments are similar to those of thepreviously described fifth and sixth embodiments.

The present embodiment is based on the Japanese Patent Application(Patent Application 2001-283322) filed on Sep. 18, 2001 and thus thecontents of this patent application are taken into the presentembodiment as reference.

Now, FIGS. 19˜21 show a ninth embodiment of the mode for carrying outthe invention, corresponding to Claim 3. A rolling bearing with a sealplate 125 a according to the present embodiment is incorporated into therotation support portion of a driven pulley 124 a which is used to driveand rotate a compressor for a car air conditioner. By the way, in thecase of the present embodiment, an electromagnetic clutch 130 is notdisposed in the rotation support part of the pulley for a compressor.That is, in the case of the present embodiment, inside a casing 122,there is disposed a rotary shaft 121 in such a manner that it isrotatably supported by a rolling bearing (not shown). And, thenear-to-inside-diameter portion of a bracket 148 is fitted with andfixed to the outer surface of the end portion of the rotary shaft 121and, at the same time, the near-to-outside-diameter portion of thebracket 148 is connected (not through the electromagnetic clutch) to oneside (in FIG. 19, the left side) of the above driven pulley 124 athrough a torque fuse or the like which can be idled only when anexcessive torque is applied.

And, the driven pulley 124 a is rotatably supported on the periphery ofa support tube portion 123 formed in the end portion of the above casing122 by the rolling bearing with a seal plate 125 a. This rolling bearingwith a seal plate 125 a is structured such that, as shown in FIGS. 20and 21 in detail, a pair of seal plates 138 a, 138 a are disposed on thetwo end portions of a single-row deep-groove-type radial ball bearing.That is, this rolling bearing 125 a with a seal plate comprises an outerring 132, an inner ring 133, and two or more balls 134, 134 which arerolling elements. Of these composing parts, the outer ring 132 includes,in the inner peripheral surface of the middle portion thereof, asingle-row deep-groove-type outer raceway 135 having an arc-shapedsection. Also, the inner ring 133 includes, in the outer peripheralsurface of the middle portion thereof, a single-row deep-groove-typeinner raceway 136 which also has an arc-shaped section. And, the aboverespective balls 134, 134 are rotatably interposed two or more in numberbetween this inner raceway 136 and the above outer raceway 135. Also, aswill be described later in detail, the outer peripheral edge portions ofthe seal plates 138 a, 138 a are secured to securing grooves 137respectively formed in the inner peripheral surfaces of the two endportions of the above outer ring 132 and, at the same time, the innerperipheral edge portions of the respective seal plates 138 a, 138 a areslidably contacted with the entire peripheries of the outer peripheralsurfaces of the two end portions of the above inner ring 133.

And, the above outer ring 132 is fitted with and fixed to the inside ofthe inner peripheral surface of a ring-shaped member 149 fitted with andfixed to the inner surface of the above driven pulley 124 a and, at thesame time, the above inner ring 133 is fitted with and fixed to theouter surface of a small diameter portion 150 formed in one side portion(in FIG. 19, the left side portion) of the outer peripheral surface ofthe above support tube portion 123. Also, the axial-direction one endface (in FIGS. 19˜21, the right end face) of this inner ring 133 isbutted against a stepped portion 152 which is a continuous portionbetween a large diameter portion 151 formed in the other end portion (inFIG. 19, the right end portion) of the outer peripheral surface of theabove support tube portion 133 and the above small diameter portion 150.And, the above inner ring 133 is held by and between the stepped portion152 and a retaining ring 171 secured to the above small diameter portion150.

And, according to the invention, a pair of seal plates 138 a, 138 a areinterposed between the inner peripheral surfaces of the two end portionsof the outer ring 132 and the outer peripheral surfaces of the two endportions of the inner ring 133 respectively constituting the aboverolling bearing 125 a with a seal plate. Each of the seal plates 138 a,138 a, as shown in detail in FIGS. 20 and 21, is structured such that anelastic member 140 made of elastomer such as rubber is reinforced with acore metal 139 produced by forming a metal plate such as a steel plateinto a circular ring shape, whereby the seal plate 138 a is formed in acircular ring shape as a whole. The outer periphery edge portion of theelastic member 140 is projected outwardly in the diameter directionslightly beyond the outer peripheral edge of the above core metal 139,while this projected portion is secured to the above securing groove137. On the other hand, the axial-direction middle portion of the innerperipheral edge portion of the above elastic member 140 is projectedinwardly in the diameter direction sufficiently beyond the innerperipheral edge of the above core metal 139, while a seal lip 153 isformed by the projected portion.

Especially, in the case of the invention, this seal lip 153 includes amain body portion 154 formed in a substantially circular-ring shape (apartially conic tube shape) and, in the inner peripheral edge portion ofthe main body portion 154, a projecting portion 155 formed over theentire periphery thereof in such a manner that it projects outwardly inthe axial direction. Also, the main body portion 154, except for theprojecting portion 155, is formed in a partially conic tube shape which,in a free state, is inclined outwardly in the axial direction as it goestoward the inner peripheral edge thereof. And, of a pair of side wallsurfaces 144 a, 144 b of each of seal grooves 143 respectively formedover the entire peripheries of the outer peripheral surfaces of the twoend portions of the above inner ring 133, with the outside side wallsurface 144 b, there is slidably contacted the leading end edge of aprojecting portion 155 formed in the above seal lip 153 over the entireperiphery thereof in a line contact state. This outside sidewall surface144 b is inclined outwardly in the axial direction thereof as it goestoward the outside diameter side.

According to the above-structured invention, when lubricating thebearing using the grease charged into the interior of the bearing, notonly the seizure life of the grease can be enhanced but also the innerraceway 136, outer raceway 135 and the rolling surfaces of therespective balls 134, 134 can be prevented against damage. That is, incase where the pressure (internal pressure) of the space with the balls134, 134 stored therein increases due to an increase in the temperatureduring use of the bearing, this pressure acts in a direction where itpresses the leading end edge of the above projecting portion 155 againstthe above sidewall surface 144 b. Thanks to this, there is eliminatedthe possibility that the contact pressure of the sliding contact portionbetween the leading end edge of the projecting portion 155 and the sidewall surface 144 b can be lowered to thereby generate a clearance in thesliding contact portion. Rather, when the above internal pressure rises,the leading end edge of the above projecting portion 155 is positivelypressed against the above side wall surface 144 b, which can enhance thesealing property of the sliding contact portion further. Also, becausethe leading end edge of the projecting portion 155, which is disposed inthe inner peripheral edge portion of the seal lip 153 in a state whereit projects in the axial direction, is slidably contacted with the aboveouter side wall surface 144 b, these leading end edge and outer sidewall surface 144 b can be easily contacted with each other in a stablemanner. That is, since the side wall surface 144 b is inclined outwardlyin the axial direction as it goes outwardly in the diameter direction,even when the outer ring 132 is inclined in any direction with respectto the inner ring 133, the leading end edge of the above projectingportion 155 is hard to be separated from the above side wall surface.

Further, in the case of the invention, because the main body portion 154(except for the projecting portion 155) constituting the above seal lip153, when the seal lip 153 is held in a free state, is inclinedoutwardly in the axial direction as it goes toward the inner peripheraledge, the elastic deformation quantity (allowance) of the above seal lip153 can be increased and thus the pressing force of the projectingportion 155 against the above outer side wall surface 144 b can beincreased. Also, as shown in FIGS. 20 and 21, in a state where theleading end edge of this projecting portion 155 is slidably contactedwith this outer side wall surface 144 b, the two side surfaces of themain body portion 154 except for the above projecting portion 155 can beeasily inclined outwardly in the axial direction as it goes toward theinner peripheral edge or can be easily made to coincide with a virtualplane which intersects the center axis of the present seal plate 138 aat right angles. Therefore, even when a centrifugal force acts on theinner peripheral edge portion of the seal lip 153 including the aboveprojecting portion 155 because the bearing is used in a state where theouter ring 132 rotates at a high speed, the present inner peripheraledge portion can be prevented from shifting in a direction where itparts away from the outer side wall surface 144 b of the above sealgroove 143. As a result of this, even under severe conditions in whichthe temperature rises, a large partial load is applied, or the outerring rotates at a high speed, the sealing performance of the rollingbearing with a seal plate 125 a can be secured sufficiently. Therefore,when the bearing is used while grease is charged into the interiorthereof, not only the base oil of the grease can be prevented fromleaking to the outside, but also the base oil can be prevented frombeing oxidized by the air in the outside, thereby being able to enhancethe life of the grease.

Further, various foreign substances existing in the outside can beprevented from entering the space with the respective balls 134, 134stored therein, thereby being able to prevent the inner raceway 136, theouter raceway 135 and the rolling surfaces of the respective balls 134,134 against damage.

By the way, to reduce the axial-direction inclination angle α (FIG. 21)of the above main body portion 144 as much as possible is preferable inthat the force to press the above projecting portion 155 against theabove outer side wall surface 144 b can be increased in accordance withthe centrifugal force to be applied when the bearing is in operation.However, in case where the above inclination angle α is reducedexcessively, there is a possibility that the axial-direction length ofthe rolling bearing with a seal plate 125 can increase. Therefore, whenreducing the inclination angle α in the illustrated structure,preferably, the outer peripheral edge portion of the above main bodyportion 154 may be shifted more inwardly in the axial direction than theillustrated structure to thereby prevent the axial-direction length ofthe rolling bearing with a seal plate 125 from increasing. On the otherhand, in case where the above inclination angle α is increased, theforce to press the above projecting portion 155 against the above outerside wall surface 144 b in accordance with the above centrifugal forcecan be reduced, thereby being able to reduce the rotation torque of therolling bearing with a seal plate 125. In this manner, according to theinvention, by changing the above inclination angle α properly, there canbe obtained the performance that is required in accordance with the useconditions and use purposes of the rolling bearing with a seal plate.Also, the pressing force of the above projecting portion 155 against theabove outer side wall surface 144 b can also be adjusted to a desiredvalue by adjusting the shape, dimension, material and the like of theabove seal lip.

Next, FIG. 22 shows a tenth embodiment of the mode for carrying out theinvention, similarly corresponding to Claim 3. In the case of thepresent embodiment, differently from the above-mentioned ninthembodiment, three seal lips 156 a˜156 c are formed in the innerperipheral edge portions of each of a pair of seal plates 138 b. And, ofthe three seal lips 156 a˜156 c, in the inner peripheral edge portion ofthe middle seal lip 156 b that is situated in the middle portion, thereis formed a projecting portion 155 in such a manner that it projectsoutwardly in the axial direction over the entire periphery thereof and,at the same time, the leading end edge of this projecting portion 155 isslidably contacted with the axial-direction outer-side side wall surface144 b of a seal groove 143 over the entire periphery thereof. In thecase of the present embodiment, the above middle seal lip 155 bcorresponds to a seal lip as set forth in the appended claims.

And, in the case of the present embodiment, of the three seal lips 156a˜156 c, the leading edge of the outside seal lip 156 a that is situatedmost outside is opposed to the portions of the outer peripheral surfacesof the two end portions of the inner ring 133 that are shifted moreoutwardly in the axial direction than the above-mentioned respectiveseal grooves 143 with a slight clearance between them; and, on thepresent portions, there are disposed labyrinth seals. Also, the leadingend edge of the inside seal lip 156 c situated most inside is opposed tothe portion of the outer peripheral surface of the middle portion of theabove inner ring 133 that is shifted more inwardly in the axialdirection than the above seal groove 143, with a slight clearancebetween them; and, on the present portion, there is disposed a labyrinthseal. In the case of the present embodiment structured in this manner,the sealing performance can be enhanced more than the above-mentionedninth embodiment.

The remaining structures and operations of the present embodiment aresimilar to those of the above-mentioned ninth embodiment. Therefore, thesame parts thereof as the ninth embodiment are given the samedesignations and thus the duplicate description thereof is omitted here.

Next, FIGS. 23˜26 respectively show an eleventh embodiment of the modefor carrying out the invention. In the case of the present embodiment,on the inner peripheral edge portions of each of a pair of seal plates138 c, there is disposed a seal lip 157. This seal lip 157 includes acircular-ring-shaped main body portion 154 and a projecting portion 155a. Of these composing parts, the projecting portion 155 a, as shown inFIG. 25, is formed in the inner peripheral edge portion of the abovemain body portion 154 in such a manner that, in a state where the seallip 157 is held in a free state, it projects substantially in parallelto the center axis of this main body portion 154 and outwardly in theaxial direction over the entire periphery thereof. Also, in the leadingend face of the above projecting portion 155 a, there is formed a flatsurface portion 158 in which an uneven portion does not existssubstantially. Further, in the circumferential-direction portion of thisflat surface portion 158, there is formed a rectangular-shaped or anarc-shaped slight cut-away portion 159.

And, in the case of the present embodiment, the flat surface portion 158formed in the leading end face of the projecting portion 155 a of theabove seal lip 157 is slidably contacted by surface contact with theouter side wall surfaces 144 b of the seal grooves 143 formed in theouter peripheral surfaces of the two end portions of the inner ring 133over the entire periphery thereof. Also, in the thus slidably contactedstate, both of the main body portion 154 and the above projectingportion 155 a formed in the above seal lip 157 are inclined outwardly inthe axial direction as they go toward the inner peripheral edgesthereof. Also, in a section relating to a virtual plane containing thecenter axes of the above respective seal plates 138 c, a straight linein contact with the inner peripheral surface of the above projectingportion 155 a and a straight line in contact with the outer side wallsurface 144 b are made to intersect each other almost at right angles.Further, according to the present embodiment, referring to the abovecut-away portion 159, in case where the depth thereof from the leadingend edge of the above seal lip 157 is expressed as L₁ (FIG. 25), thecircumferential-direction length thereof is expressed as L₂ (FIG. 26),and the diameter of the respective balls 134 is expressed as D_(a), thedimensions of the cut-away portion 159 are restricted such that they cansatisfy the following relations, that is, L₁≦0.09D_(a), andL₂≦0.18D_(a).

According to the structure of the present embodiment structured in theabove-mentioned manner, the contact area between the leading end portionof the seal lip 157 and the outer side wall surface 144 b of the sealgroove 143 formed in the inner ring 133 can be increased. Thanks tothis, even under severe conditions, the sealing performance can besecured sufficiently; and thus, when the bearing is used while grease ischarged in the interior thereof, not only the base oil of the grease canbe prevented from leaking to the outside but also this base oil can beprevented from being oxidized by the air in the outside, thereby beingable to enhance the life of the grease.

Further, the present structure can prevent various foreign substancesexisting in the outside from moving into the space with the respectiveballs 134 stored therein, thereby being able to prevent the innerraceway 136, outer raceway 135 and the rolling surfaces of therespective balls 134 against damage.

Also, according to the invention, in a section relating to a virtualplane containing the center axes of the above respective seal plates, astraight line in contact with the inner peripheral surface of the aboveprojecting portion 155 a and a straight line in contact with the outerside wall surface 144 b are made to intersect each other almost at rightangles. This can increase the force to press the above projectingportion 155 a against the present side wall surface 144 b. Further, inthe case of the present embodiment, since the cut-away portion 159 isformed in the leading end face of the projecting portion 155 a formed inthe above seal lip 157, in a state where the leading end face of thepresent projecting portion 155 a is slidably contacted with the aboveouter side wall surface 144 b, the air of the interior of the rollingbearing with a seal plate 125 a can be discharged through a slightpassage constituted by this cut-away portion 159. Thanks to this, whenthe rolling bearing with a seal plate 125 a is in use, even when theinternal pressure of the present rolling bearing tends to rise as thetemperature thereof rises, because the air of the interior thereof isdischarged to the outside, the internal pressure thereof can beprevented from increasing. Therefore, the above seal lip 157 can beprevented from turning up, which can stabilize the seal performance bythis seal lip 157. And, in the case of the present embodiment, thedimensions of the cut-away portion 159 are regulated in the followingmanner: that is, in case where the depth thereof from the leading endedge of the above seal lip 157 is expressed as L₁ (FIG. 25), thecircumferential-direction length thereof is expressed as L₂ (FIG. 26),and the diameter of the respective balls 134 is expressed as D_(a), thedimensions of the cut-away portion 159 are restricted such that they cansatisfy the following relations, that is, L₁≦0.09D_(a), andL₂≦0.18D_(a). In this manner, in the case of the present embodiment,since the dimensions of the above cut-away portion 159 are restricted tolow levels, the air can be prevented from flowing into the rollingbearing through this cut-away portion 159 from the outside. Therefore,regardless of the existence of the cut-away portion 159, the oxidizationof the above grease can be prevented.

The remaining structures and operations of the present embodiment aresimilar to those of the ninth embodiment previously shown in FIGS.19˜21. Therefore, the same parts thereof are given the same designationsand thus the duplicate description thereof is omitted here.

By the way, the cut-away portion 159 is formed in only onecircumferential-direction portion of the leading end face of theprojecting portion 155 a formed in the seal lip 157 constituting eachseal plate 138 c. However, this cut-away portion 159 can also be formedin two or more circumferential-direction portions of the preset leadingend face. Also, in the case of the present embodiment, the leading endportion of the seal lip 157 is slidably contacted with the outer sidewall surface 144 b of the seal groove 143; but, the invention as setforth in Claim 5 can also be enforced in a state where the leading endportion of the seal lip 157 is slidably contacted with the inner sidewall surface 144 a of the present seal groove 143. However, as in thepresent embodiment, in case where the leading end portion of the seallip 157 is slidably contacted with the outer side wall surface 144 b,the leading end portion of this seal lip 157 can be prevented fromshifting in a direction where it parts away from the outer side wallsurface 144 b due to an increase in the internal pressure of the rollingbearing, thereby being able to enhance the sealing performance thereoffurther.

Next, FIG. 27 shows a twelfth embodiment of the mode for carrying outthe invention, also corresponding to Claim 4. According to the presentembodiment, three seal lips 160 a˜160 c are disposed on the innerperipheral edge portions of each of seal plates 148 d. And, a flatsurface portion 158, which is formed in the leading end face of aprojecting portion 155 a disposed on the inner peripheral edge portionof the seal lip 160 b situated in the middle position of the three seallips 160 a˜160 c, is slidably contacted by surface contact with theouter side wall surface 144 b of a seal groove 143 formed in the outerperipheral surface of each of the two end portions of an inner ring 133over the entire periphery thereof. Also, of the above three seal lips160 a˜160 c, the leading end edge of the outer seal lip 160 c situatedon the outer-most side is opposed to the portion of the end portionouter peripheral surface of the inner ring 133 that is shifted moreoutwardly in the axial direction than the seal groove 143 with a slightclearance between them, thereby providing a labyrinth seal in thepresent portion. Also, of the above three seal lips 160 a˜160 c, theleading end edge of the outer seal lip 160 c situated on the inner-mostside is opposed to the portion of the middle portion outer peripheralsurface of the inner ring 133 that is shifted more inwardly in the axialdirection than the seal groove 143 with a slight clearance between them,thereby providing a labyrinth seal in the present portion.

In the case of the present embodiment structured in this manner, sincethere are disposed the labyrinth seals that are respectively formed bythe two outer and inner seal lips 160 a, 160 c, the sealing performanceof the present embodiment can be enhanced more than the above-describedeleventh embodiment.

The remaining structures and operations of the present embodiment aresimilar to those of the eleventh embodiment previously shown in FIG.23˜26. Therefore, the same parts are given the same designations andthus the duplicate description thereof is omitted here.

By the way, the structures of the eleventh and twelfth embodimentspreviously shown in FIGS. 23˜27 can also be enforced in combination withthe structures of the ninth and tenth embodiments previously shown inFIGS. 19˜22. That is, in the ninth and tenth embodiments, arectangular-shaped or arc-shaped cut-away portion can also be formed inthe leading end face of the seal lip.

Also, a rolling bearing with a seal plate according to the invention isnot limited to the structure previously described in the ninthembodiment and shown in FIGS. 19˜21 in which, when it is used, it isincorporated into the rotation support part (which does not include anelectromagnetic clutch) for driving a compressor for a car airconditioner. For example, the rolling bearing 125 a with a seal plateaccording to the ninth embodiment previously shown in FIGS. 19˜21 can beused while it is incorporated into such a rotation support part as shownin FIG. 28 (which includes an electromagnetic clutch) for a compressorfor a car air conditioner. That is, in the case of the pulley rotationsupport part for a compressor shown in FIG. 28, an electromagneticclutch 130 is interposed between a driven pulley 124 and a rotary shaft121 and, as this electromagnetic clutch 130 is operated or not operated,these driven pulley 124 and rotary shaft 121 can be engaged with ordisengaged from each other. For this purpose, a small-diameter tubeportion 161 formed in the near-to-inside-diameter portion of a bracket148 a is fitted with and fixed to the outer surface of the portion ofthe end portion of the rotary shaft 121 that projects from a casing 122.Also, a tubular member 164 and a ring-shaped plate 165 made of magneticmaterial are connected through an elastic member 163 to theoutside-diameter side and axial-direction one side of a large-diametertube portion 162 formed in the near-to-outside-diameter portion of thebracket 148 a.

And, between the outer peripheral surface of a support tube portion 123disposed on the outer surface of the end portion of the above casing 122and the inner peripheral surface of an inside-diameter-side tube portion167 disposed in the near-to-inside-diameter portion of a ring-shapedmember 166 which is fitted with and fixed to the inner surface of theinside diameter portion of the driven pulley 124 and is formed in acircular-ring-like shape as a whole having a U-shaped section, there isinterposed the rolling bearing with a seal plate 125 a used in the ninthembodiment shown in the previously described FIGS. 19˜21. Also, asolenoid 126, which is fixed to the end face of the above casing 122, isdisposed in the internal space of the above ring-shaped member 166. Theabove ring-shaped plate 165 connected to the axial-direction one side ofthe above bracket 148 a, when the above solenoid 126 is not energized,as shown in FIG. 28, is separated from the above ring-shaped member 166due to the elastic force of the above elastic member 163; but, when theabove solenoid 126 is energized, the ring-shaped plate 165 is attractedto this ring-shaped member 166 to thereby allow the rotation power to betransmitted from the above driven pulley 124 to the above-mentionedrotary shaft 121. That is, in the case of the present embodiment, theabove solenoid 126, ring-shaped member 166, ring-shaped plate 165 andelastic member 163 cooperate together in constituting theelectromagnetic clutch 130 which is used to engage the above drivenpulley 124 and rotary shaft 121 with each other as well as disengagethem from each other.

Also, in the above-described respective embodiments, description hasbeen given of a case in which the rolling bearing with a seal plate 125a is structured by providing a pair of seal plates 138 a-138 d on asingle-row radial ball bearing. However, the rolling bearing with a sealplate according to the invention is not limited to such structure. Forexample, as in a thirteenth embodiment of the mode for carrying out theinvention shown in FIG. 29 which will be shown next and corresponds toClaim 3, even in case where a pair of seal plates 138 a, 138 a aredisposed on a double-row radial ball bearing, the invention can beenforced. In the case of the present embodiment shown in FIG. 29,double-row outer raceways 135, 135 are formed in the inner peripheralsurface of an outer ring 132 and, at the same time, double-row innerraceways 136, 136 are formed in the outer surface of an inner ring 133.And, between these sets of outer raceways 135, 135 and inner raceways136, 136, there are rotatably interposed balls 134, 134 respectivelyserving as rolling elements by two or more for each set. And, betweenthe inner peripheral surfaces of the two end portions of the above outerring 132 and the outer peripheral surfaces of the two end portions ofthe above inner ring 133, there are interposed a pair of seal plates 138a, 138 a, thereby providing a rolling bearing with a seal plate 125 b.

The remaining structures and operations of the present embodiment aresimilar to those of the ninth embodiment shown in the previouslydescribed FIGS. 19˜21. Therefore, the same parts thereof are given thesame designations and thus the duplicate description thereof is omittedhere.

Next, FIGS. 30 and 31 show a fourteenth embodiment of the mode forcarrying out the invention, also corresponding to Claim 3. In the caseof the present embodiment, the invention is applied to anintegrated-pulley-type rolling bearing 169 for use in a tensioner whichadjusts the tensile force of an endless belt such as a timing belt usedin an engine. This integrated-pulley-type rolling bearing 169 iscomposed of a pulley 168 and a rolling bearing with a seal plate 125 cto which the invention relates. Of these composing parts, the pulley 168is formed in a circular-ring shape as a whole by press working a steelplate.

Also, the above rolling bearing with a seal plate 125 c, as shown indetail in FIG. 31, is composed of a single-row four-point-contact-typeball bearing and a pair of seal plates 138 a, 138 a disposed on thepresent ball bearing. That is, each of the sections of an outer raceway135 a and an inner raceway 136 a respectively formed in the innerperipheral surface of an outer ring 132 and in the outer peripheralsurface of an inner ring 133 respectively constituting the presentrolling bearing with a seal plate 125 c has a so called Gothic-archshape which can be obtained when two arcs each having a larger radius ofcurvature than one half of the diameter of the respective balls 134, 134are made to cross each other in the middle portions thereof. Therefore,the above respective raceways 135 a, 136 a and the above respectiveballs 134, 134 are contacted with each other respectively at two points,a total of four points for every balls 134, 134. And, the outer ring 132constituting the above rolling bearing with a seal plate 125 c is fittedwith and fixed to the inner surface of an inside-diameter-sidecylindrical portion 170 formed in the near-to-inside-diameter portion ofthe above pulley 168. Also, the above inner ring 133 can be fitted withand fixed to the outer surface of a support shaft (not shown).

The remaining structures and operations of the rolling bearing with aseal plate 125 c are similar to those of the ninth embodiment shown inthe previously described FIGS. 19˜21 and thus the duplicate descriptionthereof is omitted here.

The present embodiment is based on the Japanese Patent Application(Patent Application 2002-088771) filed on Mar. 27^(th), 2002 and thusthe contents thereof are incorporated into the present embodiment forreference.

Although the invention has been described heretofore in detail and withreference to the specific embodiments thereof, it is obvious to a personskilled in the art that various changes and modifications are possiblewithout departing from the spirit and scope of the invention.

INDUSTRIAL APPLICABILITY

Further, in the above description of the first embodiment of the modefor carrying out the invention, there is shown a case where theinvention is applied to a structure including an electromagnetic clutchwhich is used to engage a pulley and rotary shaft with each other anddisengage them from each other. However, the invention can also beapplied even to a structure not including an electromagnetic clutch,provided that it can transmit the rotation power from the pulley to therotary shaft. That is, in the case of a swash-plate-typevariable-capacitance-type compressor which is disclosed, for example, inthe above-mentioned patent reference 3 or in the above-mentioned patentreference 4, by reducing the inclination angle of a swash plate down toa small value (further by reducing the inclination angle down to zero),the rotation torque of the rotation shaft of the compressor can bereduced to a very small value. In the case of such structure, in somecases, as shown in FIG. 6, without using an electromagnetic clutch, thedriven pulley 4 c and rotary shaft 1, which are rotatably supportedthrough the rolling bearing 29 on the periphery of the support tubeportion 3 formed in the end portion of the casing 2, are connected toeach other through the damping member 30 functioning as a torque fuse insuch a manner that the rotation power can be transmitted to each otherunless an excessive torque is applied. In such structure, in case where,as the above rolling bearing 29, there is used a single-rowthree-point-contact-type or four-point-contact-type radial ball bearingas shown in FIG. 6, the factors of this rolling bearing 29 arerestricted to proper values, and the position relationship between thisrolling bearing 29 and the above driven pulley 4 c is restricted asshown in the previously described FIG. 1, there can be obtained theoperations and effects of the invention. Such structure is also a targetto which the invention can be applied. When applying the invention tosuch structure, the specifications of the respective parts of the aboverolling bearing 29, which can be a single-row three-point-contact-typeor four-point-contact-type ball bearing, as well as the positionrelationship between this rolling bearing 29 and the above pulley 4 cshould be similar to those shown in the above-mentioned FIGS. 1˜2.

Also, in the second embodiment of the mode for carrying out theinvention, even when there is used a deep-groove ball bearing, anangular ball bearing or a three-point-contact ball bearing is usedinstead of the four-point-contact bearing used as a single-row ballbearing, there can be obtained similar effects as the above structure.

And, in the third to eighth embodiments of the mode for carrying out theinvention, the invention can be applied not only to the above single-rowdeep-groove-type rolling bearing but also to a three-point- orfour-point-contact-type rolling bearing and further to a double-rowrolling bearing. Especially, when the invention is applied to a rollingbearing with a seal plate which is used for grease lubrication under thesevere condition that a moment load based on an offset load is supportedand also under its outer ring is to be rotated, the durability of thisrolling bearing with a seal plate can be enhanced.

And, in the ninth to fourteenth embodiments of the mode for carrying outthe invention, even in case where, differently from the presentembodiments, a seal plate is disposed in a three-point-contact-type ballbearing in which an inner raceway or an outer raceway is contacted withrolling surfaces of the respective balls at a point and an outer racewayor an inner raceway is contacted with the rolling surfaces of therespective rolling elements at two points, at a total of three pointsfor every rolling element, the invention can be enforced.

Since the pulley rotation support apparatus as set forth in Claim 1 ofthe invention is structured and operates in the previously describedmanner, without increasing the axial-direction dimension thereof, anallowable moment load can be secured as well as heat generation and wearwhich occurs during operation can be restricted. Further, even when theinvention is used in an apparatus which must be increased in therotation and capacity thereof and must be reduced in the size thereof,the grease seizure life and the rolling element run-up allowance can besecured sufficiently. Therefore, the life of a rolling bearing to beincorporated into the above-mentioned pulley rotation support apparatusas well as the life of an endless belt provided on a pulley supported onthis rolling bearing can be extended. Thus, the present pulley rotationsupport apparatus can contribute not only to a reduction in the size ofvarious machines such as a compressor for a car air conditioner but alsoto enhancement in the performance thereof.

Further, since the present pulley rotation support apparatus isstructured and operates in the previously described manner,specifically, since the pocket opening of the retainer is disposed so asto face in the direction where the radial load is applied to the centerof the bearing, when the radial load offset with respect to the bearingcenter is applied, grease existing around the load area during thebearing operation is caused to circulate actively from the inner racewayon the pocket opening side of the retainer to the outer raceway.Therefore, when the offset load is applied, the seizure life of thegrease can be extended and thus the bearing performance can be enhanced.

Further, in the case of the pulley rotation support apparatus as setforth in Claim 2 of the invention, because it is structured and operatesin the previously described manner, it can enhance the durability of arolling bearing with a seal plate and thus can contribute towardenhancing the durability and reliability of various machinesincorporated into this rolling bearing with a seal plate.

Further, in the case of the pulley rotation support apparatus as setforth in Claim 3 of the invention, because it is structured and operatesin the previously described manner, it can secure its sealingperformance sufficiently even under severe conditions. As a result ofthis, when lubrication is executed using grease charged into theinterior of the apparatus, not only the life of the grease can beenhanced but also the respective raceways and the rolling surfaces ofthe respective rolling elements can be prevented against damage.

Further, according to the pulley rotation support apparatus as set forthin Claim 4 of the invention, since it is structured and operates in thepreviously described manner, it can secure its sealing performancesufficiently under severe conditions and, when it is used with greasecharged into the interior thereof, it can enhance the life of thegrease. Further, it can prevent various foreign substances existing inthe outside from entering a space with the respective rolling elementsstored therein, thereby being able to prevent the respective racewaysand the rolling surfaces of the respective rolling elements againstdamage. Further, even when, during use of the present apparatus, theinternal pressure of the rolling bearing with a seal plate tends torise, the air of the interior of the space can be discharged out to theoutside and thus a rise in the internal pressure can be restricted, sothat the sealing performance by this seal lip can be stabilized. And,oxidization of the grease charged into the interior of the presentapparatus can be prevented.

1. A pulley rotation support apparatus, comprising a fixed support part,a rolling bearing supported on the fixed support part, and a pulley onwhich an endless belt is disposed: the rolling bearing being asingle-row three-point- or four-point-contact-type radial ball bearingincluding an inner ring having an inner raceway on the outer peripheralsurface thereof, the inner raceway contacting with the rolling surfaceof a rolling element at one or two points, an outer ring having an outerraceway on the inner peripheral surface thereof, the outer racewaycontacting with the rolling surfaces of the rolling element at one ortwo points, a plurality of rolling elements rotatably interposed betweenthe inner raceway and outer raceway, a retainer with pockets for holdingthe rolling elements therein, and a seal plate having the outerperipheral edge portion secured to the inner peripheral surface of theouter ring and a leading end portion of a seal lip formed in the innerperipheral edge portion thereof, the seal lip slidably contacting withthe inner ring, wherein the rolling bearing is lubricated by alubricant, and at least one of the inner raceway and outer raceway iscontacted with the rolling surfaces of the rolling element at two pointsrespectively, and wherein an offset quantity being an axial-directiondistance between the width-direction central portion position of theouter peripheral surface of the pulley to be contacted with the endlessbelt and the center of the radial ball bearing is 40% or less of thepitch circle diameter of the radial ball bearing, the radial clearanceof the radial ball bearing in a state of being alone is 0.2% or less ofthe pitch circle diameter of the radial ball bearing, and the openingsof the pockets of the retainer are disposed so as to face in a directionwhere an offset load is applied with respect to the bearing center.
 2. Apulley rotation support apparatus, comprising a fixed support part, arolling bearing supported on the fixed support part, and a pulley onwhich an endless belt is disposed: the rolling bearing being asingle-row three-point- or four-point-contact-type radial ball bearingincluding an inner ring having an inner raceway on the outer peripheralsurface thereof, the inner raceway contacting with the rolling surfaceof a rolling element at one or two points, an outer ring having an outerraceway on the inner peripheral surface thereof, the outer racewaycontacting with the rolling surfaces of the rolling element at one ortwo points, a plurality of rolling elements rotatably interposed betweenthe inner raceway and outer raceway, a retainer with pockets for holdingthe rolling elements therein, and a seal plate having the outerperipheral edge portion secured to the inner peripheral surface of theouter ring and a leading end portion of a seal lip formed in the innerperipheral edge portion thereof, the seal lip slidably contacting withthe inner ring, wherein the rolling bearing is lubricated by alubricant, and at least one of the inner raceway and outer raceway iscontacted with the rolling surfaces of the rolling element at two pointsrespectively, and wherein an offset quantity being an axial-directiondistance between the width-direction central portion position of theouter peripheral surface of the pulley to be contacted with the endlessbelt and the center of the radial ball bearing is 40% or less of thepitch circle diameter of the radial ball bearing, the radial clearanceof the radial ball bearing in a state of being alone is 0.2% or less ofthe pitch circle diameter of the radial ball bearing, and the seal platehas, of the inner surfaces thereof, at least thenear-to-outside-diameter portion thereof close to the inner peripheralsurface of the outer ring, the near-to-outside-diameter portion isformed as an inclined surface or a concavely curved surface inclinedinwardly in the axial direction as it goes outwardly in the diameterdirection.
 3. A pulley rotation support apparatus, comprising a fixedsupport part, a rolling bearing supported on the fixed support part, anda pulley on which an endless belt is disposed: the rolling bearing beinga single-row three-point- or four-point-contact-type radial ball bearingincluding an inner ring having an inner raceway on the outer peripheralsurface thereof, the inner raceway contacting with the rolling surfaceof a rolling element at one or two points, an outer ring having an outerraceway on the inner peripheral surface thereof, the outer racewaycontacting with the rolling surfaces of the rolling element at one ortwo points, a plurality of rolling elements rotatably interposed betweenthe inner raceway and outer raceway, a retainer with pockets for holdingthe rolling elements therein, and a seal plate having the outerperipheral edge portion secured to the inner peripheral surface of theouter ring and a leading end portion of a seal lip formed in the innerperipheral edge portion thereof, the seal lip slidably contacting withthe inner ring, wherein the rolling bearing is lubricated by alubricant, and at least one of the inner raceway and outer raceway iscontacted with the rolling surfaces of the rolling element at two pointsrespectively, and wherein an offset quantity being an axial-directiondistance between the width-direction central portion position of theouter peripheral surface of the pulley to be contacted with the endlessbelt and the center of the radial ball bearing is 40% or less of thepitch circle diameter of the radial ball bearing, the radial clearanceof the radial ball bearing in a state of being alone is 0.2% or less ofthe pitch circle diameter of the radial ball bearing, and at least oneof the seal lips includes a substantially-circular-ring-shaped main bodyportion and a projecting portion formed in the inner peripheral edgeportion of the main body portion so as to project outwardly in the axialdirection substantially over the entire periphery thereof, the main bodyportion of the present seal lip except for the projecting portionthereof, when the present seal lip is held in free state, is inclinedoutwardly in the axial direction thereof as it goes toward the innerperipheral edge portion thereof, and, in the assembled state thereof,the leading end edge of the projecting portion is slidably contactedwith the axial-direction outer side wall surface of a seal groove formedover the entire periphery of part of the outer peripheral surface of theinner ring substantially over the entire periphery of the present sidewall surface.
 4. A pulley rotation support apparatus, comprising a fixedsupport part, a rolling bearing supported on the fixed support part, anda pulley on which an endless belt is disposed: the rolling bearing beinga single-row three-point- or four-point-contact-type radial ball bearingincluding an inner ring having an inner raceway on the outer peripheralsurface thereof, the inner raceway contacting with the rolling surfaceof a rolling element at one or two points, an outer ring having an outerraceway on the inner peripheral surface thereof, the outer racewaycontacting with the rolling surfaces of the rolling element at one ortwo points, a plurality of rolling elements rotatably interposed betweenthe inner raceway and outer raceway, a retainer with pockets for holdingthe rolling elements therein, and a seal plate having the outerperipheral edge portion secured to the inner peripheral surface of theouter ring and a leading end portion of a seal lip formed in the innerperipheral edge portion thereof, the seal lip slidably contacting withthe inner ring, wherein the rolling bearing is lubricated by alubricant, and at least one of the inner raceway and outer raceway iscontacted with the rolling surfaces of the rolling element at two pointsrespectively, and wherein an offset quantity being an axial-directiondistance between the width-direction central portion position of theouter peripheral surface of the pulley to be contacted with the endlessbelt and the center of the radial ball bearing is 40% or less of thepitch circle diameter of the radial ball bearing, the radial clearanceof the radial ball bearing in a state of being alone is 0.2% or less ofthe pitch circle diameter of the radial ball bearing, and at least oneof the two seal plates is structured such that, in the portion of theleading end face of the seal lip that is opposed to the axial-directionouter side wall surface of a seal groove, there is formed arectangular-shaped or arc-shaped cut-away portion allowing the air topass into the inside thereof, the leading end portion of this seal lipis surface contacted with the axial-direction outer side wall surface ofa seal groove substantially over the entire periphery thereof, and,regarding to the cut-away portion, in case where the depth thereof fromthe leading end edge of the seal lip is expressed as L₁, the length inthe circumferential direction thereof is expressed as L₂, and thediameter of the rolling element is expressed as D_(a), “L₁≦0.0.09D_(a)and L₂≦0.18D_(a)” is satisfied.